Abstract:
A combination of location measurement apparatuses to measure in three dimensions the location of an excavator with respect to a job site, and to further measure the location of an excavated or a topographical feature with respect to the excavator by range finding from the excavator in proximity of the feature and contemporaneously recording measurement data on a computer.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 11/925,075, filed Oct. 26, 2007, the disclosure of which is hereby expressly incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates to an earth excavating machine having a means of locating a position on the earth and/or beneath the surface of the earth and recording the same. 
     BACKGROUND OF THE DISCLOSURE 
     Excavation machines of various descriptions find application in the installation, removal, and repair of below and above ground utilities and structures. Typical below ground utilities include water mains, sewers, conduit for electrical and communications lines, electrical and communications lines installed without conduit, subway transit tunnels, water tunnels and the like. 
     Below ground installation of utilities such as electrical and communication lines removes the utility lines from the visual appearance of the landscape. The location of underground utilities is generally established in advance by design engineers and provided to persons installing the utilities in the form of drawings. Location includes not only the X-Y-axes location of the utility with respect to the surface of the earth, but also includes location on the Z-axis (e.g., the distance beneath the surface of the earth or possibly referenced to sea level). In practice, the actual location of underground utilities may deviate from the location described in preconstruction drawings because of interference below the surface of the earth resulting from rocks, or rock formation, trees, building foundations, or previously installed utilities unknown to the design engineers. In anticipation of the installation of additional below ground utilities and structures in the vicinity of a first structure, and in anticipation of possible repair or replacement of a first underground utility in a vicinity, and to prevent subsequent excavations from encountering unmarked sub-surface utility structures or sub-surface obstructions, engineers make a record of the location of the utility, as installed and possibly other sub-surface obstructions. Such locations are recorded on drawings known as “as-built drawings”. 
     Typically, multiple parties are involved in the production of as-built drawings, which subjects the process to lengthy production schedules and potential human error. A first party may prepare initial or crude as-built drawings in the field. These initial drawings may consist of red-line notations on a copy of the design drawings, the location of the as-built utility having been established by hand measurements and surveying instruments, for example. A second party may then transfer the first party&#39;s initial drawings and notes into a computer aided design tool, such as the program AutoCad™ or similar computer aided design tools, to prepare the finished as-built drawings. 
     The instant invention finds utility with excavation machines including tracked excavators, wheel-based excavators, and tractor-based backhoes. It is known to determine the location of an excavator, or other machine for adjusting and moving surface and below surface earth by means of global positioning system (GPS) devices. The GPS device determines the location of its antenna. If the antenna is located on the machine, then the geographic location point of the machine may be determined by satellite triangulation. 
     Currently, the location of a feature on a job site requires location of the GPS antenna at that location. While the location of sub-surface “as-built” features on a job site may be found by locating GPS antennas at such features, such a task has limited advantages over hand measurements and surveying instruments. Notes of measurements and transfer of the as-built measurements to drawings remains a requirement. Typically, the as-built drawings will be a condition precedent to final payment to a builder or contractor by a utility company or municipality. Furthermore, GPS signals may be obstructed within a below ground level excavation, or by neighboring building structures or terrain. 
     “Offsets” provide a useful addition to GPS location information. An offset is the distance, direction, orientation, and depth (or height) of a feature determined with respect to the location of the GPS antenna. When the offset is combined with a GPS-determined location, the location of the feature can be identified in three coordinates (X, Y, and Z). Identification of two points on a target feature discloses the orientation of the feature as well as the location of the feature. 
     SUMMARY 
     According to an embodiment of the present disclosure, a work vehicle is provided for locating a topographic feature at a job site. The work vehicle includes a chassis and a tool moveably coupled to the chassis to move earth at the job site. The tool is configured to be positioned at the topographic feature. The work vehicle also includes a positioning system that communicates data related to the geographic location of the work vehicle. The work vehicle further includes a computing system that communicates with the positioning system to determine the geographic location of the tool, the computing system determining the geographic location of the topographic feature when the tool is positioned at the topographic feature. 
     According to another embodiment of the present disclosure, a work vehicle is provided for locating a topographic feature at a job site. The work vehicle includes a chassis and a tool moveably coupled to the chassis to move earth at the job site. The tool is configured to be positioned at the topographic feature. The work vehicle also includes a positioning system that communicates data related to the geographic location of the work vehicle and a computing system. The computing system has a memory with software. The software includes instructions that, when interpreted by the computing system, perform the steps of: determining an offset from the geographic location of the work vehicle to the tool; and combining the geographic location of the work vehicle and the offset to determine the geographic location of the topographic feature when the tool is positioned at the topographic feature. 
     According to yet another embodiment of the present disclosure, a method is provided for locating a topographic feature at a job site from a work vehicle. The work vehicle includes a chassis. The method includes the steps of moving a tool relative to the work vehicle to position the tool at the topographic feature and determining the geographic location of the tool when the tool is positioned at the topographic feature, the geographic location of the topographic feature corresponding to the geographic location of the tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this disclosure, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a side elevational view of an excavator equipped with a laser rangefinder; 
         FIG. 2  is a top plan view of the excavator of  FIG. 1 , further depicting an offset from a reference station; 
         FIG. 3A  is a schematic view of a display of the present disclosure shown in a worksite mode; 
         FIG. 3B  is a schematic view of the display shown in a workspace mode; 
         FIG. 3C  is another schematic view of the display shown in the workspace mode; 
         FIG. 3D  is a schematic view of the display shown in a side view mode; 
         FIG. 4  is a side elevational view of the excavator of  FIG. 1  locating a sub-surface obstruction with the laser rangefinder; 
         FIG. 5  illustrates location of an above-ground fence post with the laser rangefinder; 
         FIG. 6  illustrates location of a pile of manufactured material for volume measurement with the laser rangefinder; 
         FIG. 7  is a side elevational view of another excavator of the present disclosure, the excavator having a bucket configured for use as a pointing tool; and 
         FIG. 8  illustrates interaction of data structures running on a computer of the excavator of  FIG. 7 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     The present disclosure concerns a combination of an identified topographic feature and an offset to an excavation machine. 
     A further embodiment of the disclosure concerns a further offset from the construction machine to a feature established by a laser range finder affixed to the excavator dipper arm. 
     A further embodiment of the disclosure concerns a further offset from construction machine to the feature established by pointing the tool at the feature. 
     A further embodiment of the disclosure concerns real time integration of the location of the feature into the data for preparation of as-built drawings. 
     A further embodiment of the disclosure concerns collection of data characteristic of topographic features. 
     A further embodiment of the disclosure concerns transmitting data characteristic of topographic features to a computer apart from the excavation machine. 
     A further embodiment of the disclosure concerns manipulation of data to characterize topographic and installation features in real time by an onboard computer. 
     With reference to  FIG. 1 , the present disclosure relates to an excavation machine  12 , illustratively a tracked excavator. Excavation machine  12  may also include a wheel-based excavator, a tractor-based backhoe, and other machines for adjusting and moving surface and below-surface earth at a job site. As shown in  FIG. 1 , excavation machine  12  includes a tracked chassis  13 , operator cab  14  supported by chassis  13 , and a bucket  28  or another digging implement that is moveably coupled to chassis  13  for moving earth at the job site. Between chassis  13  and bucket  28 , excavation machine  12  includes a first, boom arm  24  and a second, dipper arm  26 . 
     Excavation machine  12  also includes an on-board computer  80  ( FIG. 8 ) that is programmed to track and control the operation of excavation machine  12 , as discussed below. Preferably the onboard computer  80  is an appropriately programmed general purpose computer, perhaps a laptop model. It is also within the scope of the present disclosure that computer  80  may be located off-board or apart from excavation machine  12 . 
     As shown in  FIG. 2 , the geographic location of the excavation machine  12  on the earth can be determined by a global positioning system (GPS) device  30 . Specifically, GPS device  30  determines the location of a receiving antenna  34 , which is mounted at a known location on chassis  13  of excavation machine  12 , via satellite transmissions from geosynchronous satellites. In this manner, the geographic location of antenna  34  corresponds to the geographic location point of excavation machine  12 . When antenna  34  is located, GPS device  30  communicates data related to the geographic location point of excavation machine  12  to computer  80  ( FIG. 8 ), which may be represented as three coordinates (X, Y, and Z). Suitable GPS systems affording centimeter-level accuracy are available from Trimble Navigation Limited, Sunnyvale Calif., United States. 
     The present disclosure contemplates excavation machine  12  having multiple GPS antennas  34 , as shown in  FIG. 2 . In addition to determining the location of excavation machine  12 , GPS device  30  of  FIG. 2  may also determine the orientation of excavation machine  12  (e.g., angle θ of  FIG. 2 ) and the direction that excavation machine  12  is facing by comparing the data received from antennas  34 . Antennas  34  are illustratively positioned at top forward corners of operator cab  14  of excavation machine  12 . 
     For improved accuracy, GPS device  30  may utilize a reference station  32  having a known geographic location, as shown in  FIG. 2 . In this embodiment, the geographic location point of excavation machine  12  would be determined by measuring a first, variable offset A between the known geographic location of reference station  32  and antenna  34  (which depends on the location of the excavation machine  12  on the excavation job site). Reference station  32  may be located away from the excavation job site (e.g., a “differential GPS” reference station located miles away from the excavation job site), or reference station  32  may be located at or near the excavation job site (e.g., a local positioning station). Signals may be transmitted between the reference station  32  and excavation machine  12  by laser or radio frequency communication rather than as satellite signals. A typical job-site positioning by laser reference station is provided by Topcon Laser Systems Inc., Pleasanton, Calif., United States. Accuracy is promoted as a few millimeters. 
     For some applications of the invention, determination of the relative location of a topographic feature  100  on the job site is sufficient. The geographic location of the topographic feature  100  on the earth is not warranted, or required. In such instances, the GPS device  30  may be omitted, and the topographic feature  100  may be located with respect to a local job-site reference station  32  or a benchmark surveyed independently of activity related to the excavation job site. 
     The foregoing systems accurately determine the geographic location point of excavation machine  12  (i.e., the geographic location of antenna  34 ). What has heretofore not been provided is a means of locating topographic features  100 , including features on, above, or below the surface of the earth, from the operator cab  14  of the excavation machine  12 . 
     Excavation machine  12  of the present disclosure further includes means for inputting workspace data, means for storing workspace data, means for displaying workspace data, means for interacting with and manipulating workspace data, and means for outputting workspace data. The workspace data may include geographic workspace information obtained from drawings or files of the job site that are constructed via measurements taken by hand, by GPS, or otherwise. Such geographic workspace information includes information regarding the placement of above-surface and sub-surface features at the job site near excavation machine  12 , including utility lines. Such drawings can be formatted according to any number of known formats, including popular AutoCad™ formats. 
     As shown in  FIG. 8 , the means for inputting workspace data include any communication device that allows for workspace data to be provided to computer  80  of excavation machine  12 . In the present example, a USB port  60  capable of receiving a flash drive having workspace data files thereon is provided as the means for inputting. Additionally or alternatively, the means for inputting is simply a keyboard that allows a user to type in workspace data. In yet another alternative, the means for inputting may also include a wireless link or a cellular telephone modem with the ability to download or otherwise receive data. 
     Excavation machine  12  then stores the data, such as in non-volatile memory  62 , as shown in  FIG. 8 . Excavation machine  12  also provides the data to display  64 , as shown in  FIGS. 3A-3D . Display  64  is illustratively provided as a simple flat screen display tablet in operator cab  14  ( FIGS. 1 and 2 ). However, embodiments are envisioned where display  64  is a heads-up style display where images are projected or otherwise displayed on the windows of operator cab  14 . As discussed further below, the programming of computer  80  includes software that can interpret the received and stored workspace data to provide a visual representation approximating a map of the job site. Such a map includes the locations of various underground elements indicated by the received workspace data. Options are provided that allow aerial/satellite maps, such as those obtained from Google Maps or otherwise, to be combined with the workspace data so that a user can more easily correlate map positions with real-world topology of the job site. 
     The means for interacting includes software on computer  80  of excavation machine  12  that receives and integrates information regarding the geographic location of excavation machine  12  with the received and stored workspace data. In an exemplary embodiment, the software outputs the interaction visually onto display  64 . For example, the software may display, in real-time, an icon of excavation machine  12  on the map of display  64  at the appropriate geographic location point of excavation machine  12 . The geographic location of excavation machine  12  is combined with the stored map to provide a real-time, interactive representation of the job site in which excavation machine  12  is located. Such mapping informs the user by providing a visual contextual rendering of excavation machine  12  at the job site and of topographic features  100  at the job-site, as shown in  FIGS. 3A-3D . Still further, the location of implements, such as boom arm  24 , dipper arm  26 , and bucket  28  may be shown on display  64  in real-time. Additionally, information such as a semi-circular arc  66  defining the maximum reach of bucket  28  of excavation machine  12  may be depicted on display  64  in real-time, as shown in  FIG. 3C . 
     Additionally, the software may receive and integrate information regarding the geographic location and other characteristics of topographic feature  100  with the received and stored workspace data. In an exemplary embodiment, the software outputs the interaction visually onto display  64  and is able to receive inputs from an operator using computer  80  in operator cab  14 . For example, such interacting may take the form of recording the geographic location of feature  100  in non-volatile memory  62 . Such interacting may also involve marking the geographic location of feature  100  on the map on display  64 , such as by selecting a representative symbol or image from a menu on display  64 . Such interacting may further involve confirming or correcting the actual or pre-planned geographic location of feature  100 , such as by editing initial design drawings. Additionally, such interacting may take the form of recording a description of feature  100  in non-volatile memory  62 . The complete record of the identity of the feature  100  and precise measurements of the location of the feature  100  are thereby recorded in computer  80  in the form of as-built drawings. 
     The means for outputting include any communication device that allows for workspace data to be downloaded and delivered from computer  80  of excavation machine  12 . In the present example, the USB port  60  is provided as the means for outputting, as well as the means for inputting. Alternatively, the means for outputting is a wireless link or a cellular telephone modem with the ability to transmit data. After feature  100  is properly recorded in computer  80 , excavation machine  12  may output the edited workspace data to another computer (not shown), such as the computer of the project manager or the customer for billing. The outputted workspace data may be in the form of finalized as-built drawings, as-built drawings requiring consolidation or further editing, or raw data that has yet to be incorporated into as-built drawings. 
     As previously noted with respect to  FIGS. 1 and 2 , the location of GPS antenna  34  on excavation machine  12  is known to the programmers of the software onboard excavation machine  12  or is input by a user. This location of antenna  34  may be measured as having a first offset A from reference station  32 . Similarly, the relative offsets between antenna  34  and other parts of excavation machine  12  are also known or determined by the software. An offset is the distance, direction, orientation, and depth (or height) of a geographic feature  100  or machine part determined with respect to the location of antenna  34  or another location on excavation machine  12 . When the offsets are combined with the GPS-determined geographic location point of excavation machine  12  (i.e., the geographic location of antenna  34 ), the geographic location point of the feature  100  or machine part can be identified in three coordinates (X, Y, and Z). 
     In a first exemplary embodiment of the present disclosure, and as shown in  FIG. 4 , excavation machine  12  includes a laser-type rangefinder  10 . Illustratively, laser rangefinder  10  is mounted on dipper arm  26  of excavation machine  12 . Laser-type rangefinders  10  that may be useful for enabling the instant invention include products of Laser Technology, Inc., Centennial, Colo. 80112, and Schmitt Measurement Systems, Inc., Portland Oreg. 97210, both of the United States. 
     Computer  80  ( FIG. 8 ) locates laser rangefinder  10  by evaluating the relative offsets between antenna  34  and laser rangefinder  10 . A list of relevant offsets include: a second, fixed offset B between antenna  34  and swing-pin  70 ; a third, variable offset C between the swing-pin  70  and boom pin  72 ; a fourth, variable offset D between boom pin  72  and dipper pin  74  (which depends on the length and angle and direction of boom arm  24 ); and a fifth, variable offset E between dipper pin  74  and the laser rangefinder  10  (which depends on the mount position of laser rangefinder  10  and the angle of dipper arm  26 ). Fixed parameters may be known by the software onboard excavation machine  12 , either by being preset or being input by a user. Such fixed parameters may include, for example, the distance between antenna  34  and swing-pin  70 , the length of boom arm  24 , and the mount position of laser rangefinder  10  on dipper arm  26 . 
     To establish the offsets from the swing-pin  70  to the laser rangefinder  10 , several axes of rotation and optionally a linear extension in the form of the variable extension on dipper arm  26  are encountered. Suitable sensors positioned at each articulation point may be used to detect movement of excavation machine  12 . 
     The first axis of rotation is swing-pin  70 . The table of excavation machine  12  may rotate about swing-pin  70 , or in the case of a tractor-mounted backhoe, boom arm  24  may rotate about swing-pin  70 . In the case of an excavator operable with a rotating table, it may not be equipped with an actual ‘swing-pin’, nonetheless, for purposes of the description herein, such rotating table-type excavators will be discussed as if a swing-pin were present. For rotating table-type excavators, the orientation of boom arm  24  corresponds to the orientation of chassis  13  (e.g., angle θ of  FIG. 2 ). As discussed above, GPS device  30  may be capable of determining the orientation of chassis  13 , such as by using multiple antennas  34  on chassis  13 . For excavators equipped with an actual swing-pin  70 , where the orientation of boom arm  24  varies relative to chassis  13 , a rotary encoder at swing-pin  70  may be used at swing-pin  70  to provide data to computer  80  and to determine the direction of boom arm  24 . 
     Other axes of rotation include boom pin  72  (which enables rotation of boom arm  24 ) and dipper pin  74  (which enables rotation of dipper arm  26 ). The radial orientation of each axis  70 ,  72 ,  74  may be measured by a rotary encoder that is positioned to detect movement about each axis  70 ,  72 ,  74 . When combined with algorithms appropriate for the individual excavation machine  12 , computer  80  can determine the orientation of the boom arm  24 , the orientation of the dipper arm  26 , and the distance between laser rangefinder  10  and swing-pin (actual or virtual)  70 . 
     For excavation machines  12  equipped with a dipper extension (not shown), a linear encoder and appropriate algorithm provide computer  80  with the additional data required to calculate the position of laser rangefinder  10 . 
     The working environment of excavators may include uneven terrain. Chassis  13  of excavation machine  12  may be oriented such that the pitch and roll of excavation machine  12  deviates from horizontal and vertical. Pitch and roll measurements may be determined by noting the difference in location of multiple antennas  34  mounted on the operator cab  14  or elsewhere on chassis  13 . It is also within the scope of the present disclosure that pitch and roll measurements may be determined by inclinometers or other sensors oriented orthogonally and mounted on the operator cab  14  or elsewhere on chassis  13 . As a result, computer  80  may also determine the pitch and roll of boom arm  24 , dipper arm  26 , and laser rangefinder  10  through axes of rotation  70 ,  72 ,  74 . 
     In use, the operator may collect real time data of the geographic location of a feature  100  by orienting the dipper arm  26  in the direction of the feature  100  to be measured and illuminating the feature  100  with the laser rangefinder  10 . In essence, computer  80  determines a sixth, variable offset F between laser rangefinder  10  and the illuminated feature  100 . To enhance daylight visibility to the operator of the laser illumination, the signal may be enhanced by a second light color such as white or green light. Further enhancement of visibility may optionally be provided by a pattern of a second light color, such as cross-hair. 
     In an alternative embodiment, the laser rangefinder  10  may be mounted in alternative position to the dipper arm  26  of the excavation machine  12 . A suitable position would be on the chassis  13  of the excavation machine  12  adjacent to the operator cab  14 , but the embodiment is not so limited. Preferably the mounting would provide gimbal movement which would permit sighting the laser rangefinder  10  to the illumination target. When coupled with a rotary encoder, the laser rangefinder  10  may be directed to a target and illuminate the feature  100  independent of movement of the boom arm  24 , dipper arm  26 , or segments thereof. Appropriate offsets from the location of the laser rangefinder  10  and algorithms therefore would be programmed in computer  80  as in the above-discussed embodiment with the laser rangefinder  10  situated on the dipper arm  26 . Data related to the sighting direction of the laser rangefinder  10  with respect to the antenna  34  would be provided to computer  80  by rotary encoders on the gimbal mount, which gimbal mount is rigidly connection to the excavator chassis  13 . 
     Suitable laser rangefinders  10  then transmit the distance (i.e., the sixth offset F) from the laser rangefinder  10  to the illuminated feature  100  to the programmed computer  80 . Data communication between the laser rangefinder  10  and computer  80  may be hardwired, or by means of a personal area network communication such as “Bluetooth”. 
     Upon receipt of input data from the laser rangefinder  10 , computer  80  collects signals from the rotary encoders, the linear encoder if so equipped, and the GPS device  30 . In embodiments having the laser rangefinder  10  mounted on the dipper arm  26 , the length of the dipper arm  26  from the dipper axis  74  to the laser rangefinder  10  is essentially arithmetically extended to the illuminated feature  100 . The three-dimensional location of the illuminated feature  100  is calculated by combining the offsets B-F with the geographic location point of the excavation machine  12  (i.e., the geographic location of antenna  34 ) by arithmetic translation and rotation along the linkages using measurements from the aforementioned linear and rotary encoders. When the orientation of the excavation machine  12  deviates from horizontal, then appropriate adjustments of the location for pitch and roll made to the data for determination of the three-dimensional location of the illuminated feature  100 . 
     Computer  80  may calculate the three-dimensional coordinates of the feature  100  by means of the algorithms programmed for the offsets, the laser rangefinder  10  data, and the job-site positioning data. Or optionally, the raw data may be downloaded for subsequent calculation of the feature  100  location and preparation of as-built drawings, or transmitted to another remote computer (not shown) apart from the excavation machine  12 , possibly by recorded media, such as a memory chip, magnetic disk, or wireless means such as a cellular telephone modem for manipulation. 
       FIG. 4  shows a located sub-surface feature  100  in an excavation, illustratively a point on a water main  50 . Computer  80  may then provide the operator the opportunity to identify the feature  100  by appropriate description or notation, for example: “buried electrical cable” or, in the illustrated embodiment, “ten inch water main.” The as-built drawing may be edited directly by the operator onboard the excavator by modifying the initial engineering design drawing using computer  80  and display  64  provided. 
     The utility of the onboard measurement is not limited to the location of sub-surface features  100  as heretofore described. As illustrated in  FIG. 5 , above-ground features  100 , illustratively fence post  52 , may also be measured by illumination of the structure, such as the top  52   a  and bottom  52   b  of a fence post  52 . The operator illuminates the top  52   a  and bottom  52   b  the fence post  52  and initiates data collection by computer  80  for each illumination  52   a ,  52   b . Advantageously, the operator also inputs a notation associated with data collected by computer  80  from the illumination that identifies the data as that of a particular fence post  52 . The notation input may be by voice collected by computer  80  by an appropriate microphone, or the notation may be made by traditional key board and mouse user interface, or both. The collected data upon manipulation by computer  80  suitably programmed generates the location and height of a fence post  52 . The fence post may then be incorporated as a feature and appropriately located, with its associated height, on as-built drawings. If computer  80  is programmed to generate as-built drawings in addition to collecting data therefore, the operator is then afforded the opportunity to see on the display  64  that the feature registers appropriately on the drawings. 
     A further useful feature is illustrated by  FIG. 6 . When combined with the common formula for the volume of a right circular cone: V=(πr 2 h)/3, the altitude of a processed construction material is readily determined, as is the radius either from the angle α of intersection of the cone with a horizontal surface, or the difference of horizontal vectors of the laser illuminated measurements. The excavator operator then may conveniently measure the volume of a cone shaped stockpile  54  such as mined gravel, coal, or grain. The convenience of such a useful feature would enable the operator to collect data to determine a volume of material. It would therefore not be necessary for a separate survey of the stockpile  54  to determine its volume. 
     The volume of the stockpile  54  thus determined may be recorded in computer  80 , or recorded and transmitted to a central location via modem, where an appropriate charge for the stockpile  54  may be made to a customer by a central billing office. With the benefit of transmitted data, immediate and accurate data of a volume of a stockpile  54  delivered, appropriate invoicing of a customer, and cash flow of the vendor may be accelerated. Alternatively, computer  80  may be programmed to manipulate the data collected in a useful form and display the results to the operator. The resulting stockpile  54  volume information could be reported to a customer on site. 
     In summary, from the combination of the offset A between reference station  32  and the geographic location point of excavation machine  12  (i.e., the geographic location of antenna  34 ), the offsets B-E between the geographic location point of excavation machine  12  and laser rangefinder  10 , and the offset F between the laser rangefinder  10  and the illuminated feature  100 , the geographic location of the illuminated feature  100  may be determined with respect to the reference station  32 . The geographic location of the illuminated feature  100  may also be used to determine characteristics of the feature  100  (e.g., features on, above, or below the surface of the earth) from the operator cab  14  of an excavation machine  12 . As the reference station  32  may be discontinued, and its original location becomes lost, by incorporating GPS data, the geographic location of the feature  100  may be stated and recorded with respect to the earth itself. 
     In a second exemplary embodiment of the present disclosure, and as shown in  FIG. 7 , bucket  28  of excavation machine  12  is used to locate feature  100 . Specifically, tooth tip  29  of bucket  28  is used to locate feature  100 . In this second embodiment, excavation machine  12  need not include a laser rangefinder  10  ( FIG. 4 ). 
     Computer  80  evaluates offsets between tooth tip  29  of bucket  28  and antenna  34 . A list of relevant offsets include: a second, fixed offset B between antenna  34  and swing-pin  70 ; a third, variable offset C between swing-pin  70  and boom pin  72 ; a fourth, variable offset D between boom pin  72  and dipper pin  74  (which depends on the length and angle and direction of boom arm  24 ); a fifth, variable offset E between dipper pin  74  and bucket pin  76  (which depends on the length and angle of dipper arm  26 ); and a sixth, variable offset F between bucket pin  76  and tooth tip  29  (which depends on the length and angle of bucket  28 ). Again, fixed parameters may be known by the software onboard excavation machine  12 , either by being preset or being input by a user. Such fixed parameters may include, for example, the distance between antenna  34  and swing-pin  70 , the length of boom arm  24 , and the length of bucket  28 . 
     It should be appreciated that excavation machine  12  can take on different buckets  28 , or other implements, each having different sizes and shapes, thus producing different offsets associated therewith. Accordingly, the identity of bucket  28  is also provided to computer  80 . While the raw measurement data of bucket  28  can be provided to computer  80 , the computer  80  may also have pre-stored configuration files that provide the offset data for various common buckets. Different buckets  28  can be identified to the computer  80  via user entry, or through an automated means, such as an RFID reader located near the end of dipper arm  26  (and in communication with the computer  80 ) and a RFID tag located on bucket  28 . 
     In use, the operator of excavation machine  12  places tooth tip  29  of bucket  28  as close as possible to feature  100 . In other words, the operator uses tooth tip  29  of bucket  28  as a pointer to identify and locate feature  100 . Skilled operators may be able to place tooth tip  29  within 2 inches, 1.5 inch, 1 inch, 0.5 inch, or less of feature  100  without actually having to contact feature  100 , all of which are within an acceptable as-built drawing tolerance of about 4 inches, for example. When tooth tip  29  is located near feature  100  (which may be confirmed by pressing a “start” button or another user input), computer  80  collects signals from the rotary encoders, the linear encoder if so equipped, and the GPS device  30 . The computer  80  uses this collected information to calculate the offsets B-F between the tooth tip  29  and the geographic location point of the excavation machine  12  (i.e., the geographic location of antenna  34 ) and to determine the geographic location point of the feature  100  near the tooth tip  29 . It is within the scope of the present disclosure that the computer  80  may add a nominal value to sixth, variable offset F between bucket pin  76  and tooth tip  29  to account for the fact that tooth tip  29  may not directly contact feature  100 . 
     The display  64  of  FIGS. 3A-3D  is illustratively a touchscreen that includes a plurality of buttons. Such buttons include informational buttons  67  that give context to what is being viewed. Examples of informational buttons  67  are ones that indicate whether a worksite is being shown, a workspace is being shown, or a side view is being shown on display  64 . When a worksite is shown, as in  FIG. 3A , the north side of the map may be oriented upward on display  64 . By contrast, when a workspace is shown, as in  FIGS. 3B and 3C , a zoomed in, more local map may be displayed from the perspective of the operator in cab  14 . When a side view is shown, as in  FIG. 3D , the position of bucket  28  may be shown in real-time relative to chassis  13  of excavation machine  12 . Display  64  may also depict a target trench T, as well as communicate the current distance between bucket  28  and the grade line G and the current distance between bucket  28  and benchmark line B. 
     The buttons on display  64  may also include command or input buttons  68  that allow the user to alter display  64  and perform various tasks. Command buttons  68  may be organized in customizable menus for ease of use, as set forth below. 
     When informational button  67  indicates that a worksite is being shown, as in  FIG. 3A , the user may select one or more of the following command buttons  68 : “zoom,” “pan,” and “select scene,” for example. The “zoom” button allows the user to zoom in or out of the map. The “pan” button allows the user to translate the map across display  64 . The “select scene” button allows the user to customize the map view, such as by layering in aerial/satellite views, elevational views, grid lines, utility lines, or other scenes, for example. 
     In the worksite view, the user may also select one or more of the following command buttons  68 : “dig” and “segment complete,” for example. The “dig” button allows the user to specify or define a custom trench for digging (e.g., a target start location, a target depth, a target slope). After inputting the appropriate data, computer  80  may automatically generate a target, phantom icon of excavation machine  12  at the target start location. In use, the operator may drive excavation machine  12  until the actual icon of excavation machine  12  overlaps the target icon of excavation machine  12 . It is also within the scope of the present disclosure that steering of excavation machine  12  may be performed automatically to drive excavation machine  12  to the target start location. After digging the custom trench, the user presses the “segment complete” button, which automatically records the completed trench and inputs the completed trench into the as-built drawings. The user may also assign a color to the completed trench corresponding to the anticipated use of the completed trench. 
     When informational button  67  indicates that a workspace is being shown, as in  FIGS. 3B and 3C , the user may select one or more of the following command buttons  68 : “zoom,” “select scene,” “tool tip left/right,” and “measure.” The “zoom” and “select scene” buttons may have the same function as in the worksite mode. The “tool tip left/right” button allows the user to specify which tooth tip  29  of bucket  28  (e.g., the left-most tooth tip  29  or the right-most tooth tip  29 ) will be used for pointing. In this manner, the user can avoid pointing with the hidden, central portion of bucket  28  and can instead point with an exposed, side portion of bucket  28 . Computer  80  will compute the offset to the selected tooth tip  29  of bucket  28  to properly locate feature  100  relative to the selected tooth tip  29 . The selected tooth tip  29  may be highlighted or circled on display  64  to remind the user of the active tooth tip  29 . In the illustrated embodiment of  FIG. 3C , for example, the left-side tooth tip  29  is active and circled on display  64 . The “measure” button allows the user to specify a desired measurement (e.g., length, slope, area, volume) and corresponding input points for measuring by computer  80 . Returning to  FIG. 5 , for example, the user may point to top  52   a  of fence post  52  and to bottom  52   b  of fence post  52  and then request a length measurement of fence post  52  between top  52   a  and bottom  52   b . As another example, the user may point to multiple vertices of a closed polygon and then request an area measurement for the space defined between the vertices. 
     In the workspace view, the user may also select a “modify” button, which allows the user to locate, add, and edit features on the map of display  64 . The “modify” button may allow the user to add a new feature  100  to the map by pointing to the new feature  100  with bucket  28 . When adding a new feature  100 , display  64  may automatically generate a menu of symbols or images to label the new feature  100  on the map. For example, the user may select an octagon-shaped symbol when pointing to the location of a manhole, a square-shaped symbol when pointing to the location of an enclosure, a star-shaped symbol when pointing to the location of a power pole, and a circled-M symbol when pointing to the location of a gas meter. Other symbols and features are within the scope of the present disclosure. The “modify” button may allow the user to move, edit, or delete mapped features  100 . In this manner, the operator is able to prepare and edit as-built drawings from operator cab  14  of excavation machine  12  during the excavation process. 
     When informational button  67  indicates that a side view is being shown, as in  FIG. 3D , the user may select one or more of the following command buttons  68 : “tool tip left/right,” “set benchmark,” and “calibrate.” The “tool tip left/right” button may have the same function as in the workspace mode. The “calibrate” button may allow the user to specify certain settings and measurements, such as the dimensions of bucket  28 . The “set benchmark” button may allow the user to define a custom trench T for digging, such as by inputting the target depth and the target slope of the trench T. During the digging process, the user may refer to the side view of  FIG. 3D  to ensure that bucket  28  is reaching the desired depth. It is also within the scope of the present disclosure that computer  80  may automatically manipulate boom arm  24 , dipper arm  26 , and bucket  28  to dig the desired trench T. 
     The display  64  may also show exclusion zones around buried utility lines, as discussed in U.S. patent application Ser. No. 13/214,869, entitled “Buried Utility Data with Exclusion Zones,” filed Aug. 22, 2011, the disclosure of which is hereby expressly incorporated by reference herein in its entirety. 
     With reference to  FIG. 8 , the software running on computer  80  includes a plurality of data structures. Such data structures include data structures for importing map data  1000 , for storing map data  1010 , for retrieving map data  1015 , for interfacing with a GPS device  1020 , for calculating machine orientation  1025 , for receiving implement relative positioning data  1030 , for calculating implement absolute positioning data  1040 , for implementing exclusion zones  1050 , for displaying map and positioning data  1060 , for receiving user input  1070 , for recording map and positioning data  1080 , and for outputting map data  1090 . 
     The data structure for importing map data  1000  interfaces with USB port  60  (or other similar interface) to obtain map data. This data is passed to the data structure for storing map data  1010 . The data structure for storing map data  1010  interfaces with memory  62  to store the map data. The data structure for retrieving map data  1015  interfaces with memory  62  to retrieve previously stored map data. The data structure for interfacing with a GPS device  1020  communicates with GPS device  30  (which includes the plurality of antennas  34 ) to obtain GPS coordinates for antennas  34 . The data structure for calculating machine orientation  1025  takes the obtained GPS coordinates and determines the position of excavation machine  12  as well as compares the GPS readings from each antenna  34  to determine the orientation of excavation machine  12 . 
     The data structure for receiving implement relative positioning data  1030  interfaces with display  64  for any user input data regarding the particular implement being used (or alternatively with another indicator of the implement, such as an RFID reader). Structure  1030  also interfaces with sensors monitoring boom arm  24 , dipper arm  26 , bucket  28 , swing pin  70 , boom pin  72 , dipper pin  74 , and bucket pin  76 . These sensors allow computer  80  to calculate the relative position of each piece  24 ,  26 ,  28 ,  70 ,  72 ,  74 ,  76  to antennas  34 . This relative positioning data is then passed to structure  1040 . 
     The data structure for calculating implement absolute positioning data  1040  takes the relative positioning data from structure  1030  and combines it with the GPS positioning and orientation data from structure  1025  to determine the physical space inhabited by each piece  24 ,  26 ,  28 ,  70 ,  72 ,  74 ,  76 . The data structure for displaying map and positioning data  1060  takes the passed data and presents an integrated data set to display  64 . 
     The data structure for receiving user input  1070  allows a user to interact with display  64  to alter the displayed map and to otherwise initiate other data structures, such as by locating and labeling a new feature on the map. Structure  1070  also receives input regarding desired movement of excavation machine  12 , including movement of pieces  24 ,  26 ,  28 ,  70 ,  72 ,  74 ,  76 . 
     The structure for recording map and positioning data  1080  takes the integrated data set from structure  1070  and records the integrated data set to memory  62 . The recording structure  1080  may overwrite the originally input map data with the edited map data. Also, the recording structure  1080  may act based upon a user&#39;s save request or automatically after a predetermined time. 
     The data structure for outputting map and positioning data  1090  interfaces with USB port  60  (or other similar interface) to transmit map data, which may be in the form of as-built drawings. 
     Many of the data structures are implemented in an iterative fashion such that the map on display  64  is constantly being redrawn and the position of excavation machine  12  and its parts is constantly being reassessed. In this way, a real-time representation of excavation machine  12  at the job site is presented on display  64 . 
     To summarize, the system described and claimed may provide the three-dimensional geographic location (X, Y, and Z axis) and dimension of several characteristics of topographic features  100  such as: the dimensions of an excavation; the volume of a feature; the location and height of an above-ground feature; the slope of a surface; the location of a sub-surface utility; or the location of a sub-surface obstruction, all from the operator cab  14  of excavation machine  12 . 
     As illustrated by a simplified example of a right circular cone ( FIG. 6 ), other measurements of angles, slopes, grades and volumes are readily accomplished from the operator cab  14  of excavation machine  12 . 
     While this invention has been described as having exemplary designs, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.