Device for assisting a user to draw a topographical contour map

A device for use in plotting equal spacings over a distance includes a frame comprising opposed first and second pairs of frame members with each frame member having opposed ends and pivotal connecting means for pivotally connecting adjacent frame members at respective ends thereof. Each of the first pair of frame members includes a plurality of longitudinally spaced-apart apertures disposed along its respective length. The device further includes a flexible linear member placed continuously through the apertures of said first pair of frame members to provide a plurality of parallel equally spaced apart linear elements which are disposed in substantially parallel relation with each other and with the second pair of frame members, and a marker element being slidably attached to each of the plurality of linear elements.

FIELD OF THE INVENTION
 The present invention generally relates to a device for assisting a user to
 draw a topographical contour map, more particularly to devices for use in
 indicating equal spacings between two terminal points of a line or
 distance so that a topographical contour map may be accurately drawn
 therefrom.
 BACKGROUND OF THE INVENTION
 When using the stadia method (the plotting of points) of making a
 topographical contour map, engineers and surveyors have experienced
 difficulty in precisely drawing the lines or contours necessary to provide
 an accurate display of the topography of a finite parcel of land. In
 particular, the topographical lines are drawn based on a series of points
 plotted in generally a minimum of three directions. The plotted points
 each represent a certain elevational unit or elevation (e.g. 1 foot).
 Interpolation is necessary to precisely position the contour lines,
 especially when the total elevation requires a fraction of a unit.
 Although certain devices have been developed for the purpose of addressing
 the problem, the prior art devices are generally expensive, bulky, and
 difficult to use.
 It would be of significant advance in the art of producing topographical
 contour maps to develop a device having a durable, compact construction
 and design which facilitates the positioning of points to enable the
 drawing of accurate, low-cost topographical contour maps.
 SUMMARY OF THE INVENTION
 The present invention is generally directed to a device for assisting a
 user in drawing a topographical contour map through the plotting of
 multipoints in multiple directions comprised of a frame including opposed
 first and second pairs of frame members where each of the frame members
 has ends that are pivotally connected to the ends of adjacent frame
 members so that the frame be readily moved to assume a variety of
 parallelogram shapes, and a plurality of equally spaced-apart linear
 elements extending between the first pair of frame members wherein the
 distance between the spaced apart elements changes as the shape of the
 parallelogram changes. The shape of the frame and therefore the distance
 between the linear elements may be adjusted to plot points for the
 formation of contour lines on a topographical contour map regardless of
 the steepness of the grade of elevation. The device enables the points to
 be plotted in a manner which is visually easy to read. The device is also
 portable with a durable construction.
 In one aspect of the present invention there is provided a device for
 assisting in the formation of a topographical contour map which comprises:
 a frame including opposed first and second pairs of frame members with each
 frame member having opposed ends;
 pivotal connecting means for pivotally connecting adjacent frame members at
 respective ends thereof; and
 a plurality of equally spaced-apart linear elements extending between the
 first pair of frame members with alternate linear elements being
 distinguishable from adjacent linear elements.
 In another aspect of the present invention, the device comprises:
 a frame including opposed first and second pairs of frame members with each
 frame member having opposed ends;
 pivotal connecting means for pivotally connecting adjacent frame members at
 respective ends thereof;
 a plurality of longitudinally spaced apart apertures disposed along the
 length of each of the first pair of frame members;
 a single linear member being continuously placed through the apertures to
 provide a plurality of parallel equally spaced apart linear elements which
 are disposed in substantially parallel relation with each other and with
 the second pair of frame members; and
 a marker element being slidably attached to each of the plurality of linear
 elements.

DETAILED DESCRIPTION OF THE INVENTION
 The present invention is generally directed to a device for assisting the
 user in drawing a topographical contour map. The device is constructed in
 a manner that provides a simple and inexpensive tool for plotting points
 to facilitate the formation of topographical contour maps and other
 graphical representations. The device is easy to use and affords accurate
 plotting which enables the drawing of topographical contour maps which
 precisely depict the contour or elevation of a finite parcel of land. The
 device is portable and compact making it especially useful for engineers
 and surveyors working on-site under various lighting and weather
 conditions. In addition, the device may be constructed in a manner which
 allows the user to carry the device is the pocket.
 Referring to FIG. 1, a device 10 is illustrated for one embodiment of the
 invention. The device 10 includes a frame 12 having a general
 parallelogram shape where the angles of the parallelogram can change as
 hereinafter described. The frame 12 has a pair of opposed generally
 shorter frame members 14 and 16 pivotally connected to another pair of
 opposed generally longer frame members 18 and 20 at their respective ends
 by a pivot assembly 22. The frame members 14, 16, 18 and 20 and the pivot
 assemblies 22 may be constructed of any suitable durable, rigid material
 such as metal, wood, plastic, carbon composite, and the like, which can
 withstand the rigors of constant flexing and pivot movement. The frame
 members 18 and 20 further include a plurality of longitudinally spaced
 apart apertures 24 which are used to house and align linear members as
 hereinafter described. The plurality of spaced apart apertures 24 are
 axially aligned with the center of the adjacent pivot assemblies 22
 between the frame members 14, 16, 18 and 20 of the frame 12.
 A single, flexible linear member 26 is threaded alternately between each
 member 18, 20 beginning at the endmost aperture and continuing
 successively through corresponding apertures 24 to provide a plurality of
 parallel equally spaced linear elements 28. The linear member 26 may
 include, but is not limited to, thread, fiber, string, cord, wire made of
 metal, plastics, and the like. In this embodiment, the device 10 includes
 thirty-three linear elements 28 which are spaced apart by 3/16 inch when
 the frame 12 is straight and squared. It will be understood that the
 number of and the distance between the linear elements 28 may be varied as
 desired by the modifying the number and spacing of the apertures 24 in the
 device 10.
 The opposite ends of the linear member 26 may be securely anchored by knots
 (not shown) which are larger than the diameter of the apertures 24. It
 will be understood that other means for anchoring of the ends may be used.
 As shown in FIG. 1, one end of the linear member 26 is anchored on one
 member 20 and the other end of the linear member 26 is anchored on the
 other opposed member 18.
 It will be noted that, when each member 14,16,18,20 of the frame 12 is
 arranged in substantially right angular relation with an adjacent member,
 the spacing between the linear elements 28 is at its maximum. However,
 when adjacent frame members are shifted out of right angular relationship
 with respect to each other, the distance between the linear elements 28
 will progressively decrease.
 To divide a given distance or line into a number of equal spaces, the frame
 12 of the device 10 is adjusted until the outermost two linear elements,
 which encompasses a number of linear elements therebetween, are in
 alignment with terminal points of the distance or line to be divided.
 Smaller spaces are obtained by partially closing the frame 12 or shifting
 the frame 12 so that adjacent frame members are progressively shifted away
 from right angular relation. Therefore, for example, if a line or a
 distance is to be divided by the device 10 into ten equal spaces, the
 spacing is accomplished by shifting the frame 12 until the outermost
 linear elements 28 encompassing nine linear elements 28 therebetween, are
 in alignment with the respective ends of the line. It will be understood
 that if a line or distance to be divided is greater than the distance
 between the two outermost linear elements 28 when the frame 12 is in its
 fully opened position, then the frame 12 may be shifted so that the linear
 elements 28 are shifted from a normal or perpendicular relation with
 respect to the frame members to a more angular position with these frame
 members. This reduces the spacing between adjacent linear elements to
 permit a larger number of linear elements 28 to be utilized in dividing
 the line or distance into equal increments.
 As to using the device 10 for drawing topographical contour maps, a map
 indicated with a series of vertically and horizontally running grid lines
 may be utilized. However, it will be understood that maps without grid
 lines may also be used with the device 10. Through known methods of
 surveying land, the user can determine the corresponding elevations at
 select points on the map, for example, at the points intersected by the
 grid lines. The user begins by selecting two neighboring known elevation
 points. Knowing the difference in elevation between the two elevation
 points, the user determines the number of linear elements 28 of device 10
 needed for plotting one or more intermediate elevation points, for
 example, selecting one linear element 28 for each unit change in
 elevation. The frame 12 of the device 10 is then adjusted until the two
 outermost linear elements 28, which encompasses the selected number of
 linear elements 28 therebetween, are respectively in alignment with the
 two known elevation points on the map. The user marks off the intermediate
 elevation points as indicated by each linear element 28. The process is
 repeated throughout the grid or area of the map for plotting the
 intermediate elevation points. Upon completion, the user draws the contour
 lines through the associated elevation points as plotted.
 Referring again to FIG. 1, each of the frame members 18 and 20, further
 includes a sequence of numbered markings 30, each of which corresponds to
 an associated aperture 24 and linear element 28. The markings 30 provide a
 visually efficient way of counting off the number of linear elements 28
 that the user may need to plot which provides better accuracy and speed.
 Rather than physically counting each linear element 28 which may introduce
 error and slow the plotting, the user simply glances at the desired number
 and then look to the linear element 28 immediate to the number marking 30.
 The plurality of linear elements 28 may further include alternate linear
 elements 28 being distinguishable from adjacent linear elements 28. This
 effect may be accomplished by generating a visually distinctive scheme
 which alternates between each linear element 28. Such visually distinctive
 schemes may include color coding each linear element 28 alternately
 between two contrasting colors, for example, providing the user with a
 facilitated means for visually pinpointing a specific linear element 28
 during the plotting process. In a preferred embodiment, the plurality of
 linear elements 28 may include a red and white color scheme for providing
 improved visual distinguishment. It will be appreciated that other
 alternating visually distinctive schemes may be used as desired such as
 using different surface textures, translucence, visual patterns, and the
 like.
 As shown in FIG. 1, all or some of the linear elements 28 may include a
 marker element 32 slidably connected thereto as shown specifically in FIG.
 1 where a marker element 32 is provided on alternating linear elements 28.
 The marker element 32 is configured to selectively slide along the length
 of the corresponding linear element 28. The marker elements 28 of the
 outermost linear elements 28 may be positioned over the corresponding
 terminal points for better visibility and ease of use. The marker elements
 28 provides the user with a rapid means for ensuring that the device 10 is
 correctly aligned with terminal points of the distance to be divided and
 that the correct number of linear elements 28 is apportioned thereto.
 Referring to FIG. 2, a cross sectional view of the member 20 is shown. The
 edge portion 34 proximate to the apertures 24 is tapered for permitting
 the user to easily match the numbered markings 30 with the corresponding
 ends of the linear elements 28 from various perspective views. The opposed
 member 18 includes the same cross sectional profile as member 20.
 Referring to FIG. 3, a cross sectional view of the assembled frame members
 16, 18 and 20 is shown with the plurality of linear elements 28 extending
 between the frame members 18 and 20. The pivot assembly 22 comprises a
 machine screw 38 which extends through a washer 42 and an opening 36 in
 each of the associated frame members 14, 16, 18, and 20, and a wing nut 40
 threadedly engaged with the machine screw 38. The wing nuts 40 may be
 tightened to generate a frictional engagement of the contacting faces
 between each member 14, 16, 18, 20 and permit the device 10 to be remained
 in an adjusted position. Alternatively, a nut and bolt assembly may be
 used for the pivot assembly 22. The coefficient friction of the suitable
 durable, rigid material employed permits the frame members to be retained
 in a selected position until forcibly shifted to a new position. However,
 the pivot assembly 22 is not limited to the arrangements described above
 and may include other mechanisms and devices which permit selective swivel
 movement between the frame members of the frame, as known to one of
 ordinary skill in the art. It is preferable to overlap the frame members
 14 and 16 over the opposed pairs of frame members 18 and 20, thereby
 minimizing the distance between the plurality of linear elements 28 and
 the plotting surface for better accuracy and precision.
 The foregoing discussion discloses and describes merely exemplary
 embodiments of the present invention. One skilled in the art will readily
 recognize from such discussion, and from the accompanying drawings and
 claims, that various changes, modifications and variations can be made
 therein without departing from the spirit and scope of the invention as
 defined in the following claims.