Method for optically scanning and measuring an environment

A method for optically scanning, measuring and displaying a point cloud is provided. The method includes emitting, by a laser scanner, an emission light beam and receiving a reflection light beam that is reflected from an object. A control device determines for measurement points projected on a plane corresponding to a screen, wherein at least some measurement points are displayed on a display device. One or more pixels are gap filled to generate a visual appearance of a surface on the display device. Wherein the gap filling includes a first horizontal search in a first direction of a first measured point of the measurement points followed by a second horizontal search in a second direction of the first measured point. The gap filling further includes a first vertical search in a third direction of the measured point, followed by a second vertical search in a fourth direction.

BACKGROUND

The invention relates to a system and method for optically scanning and measuring an environment, and in particular, to a system and method for generating a display image from a point cloud.

Metrology devices, such as laser scanners for example, may generate large volumes of coordinate data of points located on the surfaces of the scanned area. These types of devices may be used to generate three-dimensional models of an area, such as a home or building, a crime scene, or an archeological site for example. Often with these types of scans, the data may be acquired from multiple positions to capture all of the desired surfaces and avoid having blank areas where a surface was in the “shadow” of another object. As a result in several data-sets of coordinate data are generated that are registered together to define a single data-set, sometimes colloquially referred to as a “point cloud” since the data is represented as a group of points in space without surfaces.

It should be appreciated that from a graphical display of a point cloud, it may be difficult to visualize the surfaces of the scanned area. This is due to the close proximity of points (from any user point of view) within the point cloud that may lie on different planes. For example, if the user point of view of the point cloud is looking down on a table, there will be points within the field of view from the table surface, along with the floor that is underneath the table surface or even the surface on the underside of the table.

Where the point cloud is relatively dense, meaning that the points on a surface are dense, the generation of surfaces in the displayed image for visualizing the scanned area may be created, albeit computationally intensive. However, in some applications, the point cloud may have a lower density of points resulting in gaps in the data set between the points of the point cloud. As a result, it may be difficult to generate a desired displayed image.

Accordingly, while existing metrology devices and point cloud display systems are suitable for their intended purposes the need for improvement remains, particularly in providing a system for filling in pixels on a graphical display to generate a displayed image of a point cloud.

SUMMARY

According to an embodiment of the present invention a method for optically scanning, measuring and displaying a point cloud is provided. The method includes emitting, by a light emitter of a laser scanner, an emission light beam. A light receiver receives a reflection light beam, wherein a reflection light beam of the emission light beam is reflected from an object. A control and evaluation device determines for measurement points projected on a plane corresponding to a screen on a display device, at least the distance from the object to a center of the laser scanner, wherein at least some measurement points are displayed on the display device. The points are visible are determined on the display device based at least in part on a viewpoint of the display device. One or more pixels are gap filled to generate a visual appearance of a surface on the display device. Wherein the gap filling includes a first horizontal search in a first direction of a first measured point of the measurement points followed by a second horizontal search in a second direction of the first measured point, the second direction being opposite the first direction. The gap filling further includes a first vertical search in a third direction of the measured point, the third direction being perpendicular to the first direction, followed by a second vertical search in a fourth direction, the fourth direction being opposite the third direction.

DETAILED DESCRIPTION

Referring toFIG. 1andFIG. 2, a laser scanner10is provided as a device for optically scanning and measuring the environment of the laser scanner10. The laser scanner10has a measuring head12and a base14. The measuring head12is mounted on the base14as a unit that can be rotated about a vertical axis. The measuring head12has a rotary mirror16that can be rotated about a horizontal axis. The point of intersection between the two axes of rotation is designated as the center C10of the laser scanner10.

The measuring head12also has a light emitter17for emitting an emission light beam18. The emission light beam18may be a laser beam in the range of wavelength of approximately 300 to 1600 nm, for example, 790 nm, 905 nm or less than 400 nm, but other electro-magnetic waves having, for example, a greater wavelength can be used. The emission light beam18may be amplitude-modulated with, for example, a sinusoidal or rectangular-waveform modulation signal. The emission light beam18is passed from the light emitter17onto the rotary mirror16where it is deflected and then emitted into the environment. A reception light beam20, which is reflected by or otherwise scattered from an object O, is captured again by the rotary mirror16, deflected and passed onto a light receiver21. The direction of the emission light beam18and of the reception light beam20results from the angular positions of the rotary mirror16and the measuring head12, which depend on the positions of their respective rotary drives which are, in turn, detected by a respective angular encoder.

A control and evaluation device22has a data link connection to the light emitter17and to the light receiver21in the measuring head12, parts thereof being arranged also outside the measuring head12, for example as a computer connected to the base14. The control and evaluation device22determines, for a multiplicity of measurement points X, the distance d of the laser scanner10from the illuminated point on the object O (e.g. the table T,FIG. 3), and from the propagation times of emission light beam18and reception light beam20. In an embodiment, the distance d is determined by the control and evaluation device22based on the phase shift between the two light beams18and20. In another embodiment, the distance d is determined by the control and evaluation device based on a measured round trip time between an outgoing emission pulse of light18and a returning reception pulse of light20. In another embodiment, the distance d is determine by the control and evaluation device based on change in optical wavelength of a reception beam of light20relative to an emission beam of light, the emission beam of light having an optical wavelength that is linearly swept (chirped) in time. Many other methods are known in the art and may be used to determine the distance d.

Through use of the relatively rapid rotation of the mirror16, scanning takes place along a circular line. Also, through use of the relatively slow rotation of the measuring head12relative to the base14, the entire space is gradually scanned with the circular lines. The totality of the measurement points X of such a measurement may be referred to as a scan. The center C10of the laser scanner10defines for such a scan the origin of the local stationary reference system. The base14is stationary in this local stationary reference system. In other embodiments, a different type of beam steering method is used to direct the emission beam18to different points X in the environment. In an embodiment, a pair of galvanometer steering mirrors are used to rapidly direct the emission beam18to desired points X. In another embodiment, the emission beam18rotates along with the entire measuring head12. Many types of beam steering mechanisms are known in the art and may be used.

In addition to the distance d to the center C10of the laser scanner10, each measurement point X comprises a brightness value which may also be determined by the control and evaluation device22. Here the term brightness may be understood to refer to a level of optical power or a level of irradiance (optical power per unit area). The brightness is a gray-tone value which is determined, for example, by integration of the bandpass-filtered and amplified signal of the light receiver21over a measuring period which is assigned to the measurement point X. Through use of a color camera, it is optionally possible to generate pictures, by which colors (R, G, B) can be assigned as a value to the measurement points X in addition to the brightness or comprising the brightness.

A display device30is connected to the control and evaluation device22. The display device30can be integrated into the laser scanner10, for example into the measuring head12or into the base14, or it can be an external unit, for example part of a computer which is connected to the base14. The display device30has a graphics card32and a screen34which can be arranged separately from one another or as a structural unit. The control and evaluation device22provides 3D data of the scan.

It should be appreciated that when the measurement points X, which are positioned in a three-dimensional space, are displayed on a two-dimensional display device30, it may be difficult for the user to visualize the object O on the display. For example, referring toFIG. 3a table T has been scanned with the laser scanner10and the measurement points X have been acquired. When the user displays the measurement points X from a viewpoint V, the user will see not only the measurement points XTfrom the tabletop, but also the measurement points XF. As a result, without a visual reference such as a surface of the table T or the surfaces of the legs of the table, it will be difficult for the user to distinguish between the measurement points XTand the measurement points XF. It should be appreciated that in an embodiment where the measured object O is a structure, such as the inside of a building and the measured points may be on opposite sides of a wall. Accordingly, embodiments herein provide advantages generating on display device30an image representing surfaces on the object O by filling in the pixels between measured points. The method of filling in the pixels between the measured points may sometimes be referred to a gap filling or pixel filling.

In many cases, objects in an environment are scanned with a laser scanner10placed in a plurality of locations. This is illustrated inFIG. 3, where a scanner10A is located at a first location at a first time and the same or different scanner10B is located at a different location at a second time. In some embodiments, multiple scanners such as10A,10B are used simultaneously. In an embodiment, the scanner10A is positioned to scan the top side of the table T and to a lesser extent floor points to the side of the table. The scanner10B is positioned to scan mostly points beneath the table T rather than on top of the table. When the measurement points XTare registered with the measurement points XF, the result is a point cloud having points distributed over three-dimensional space. From the perspective of a viewer V, such a collection of sparsely located points may not clearly indicate which points are closer to the viewer and which are farther from the viewer. Hence a display of the collected points in the point cloud may intersperse the floor points and the tabletop points, with the surfaces not clearly distinguished for the viewer V.

Referring now toFIGS. 4-7, with continuing reference toFIG. 1andFIG. 2, the graphic card32converts the 3-D data into 2-D data (e.g., rendering data), which are displayed on the screen34. The 3-D data are the measurement points X, wherein several scans from different positions of the laser scanner10can be assembled into one scene. For representing the 2-D data, there are pixels P, i.e., adjacent, small polygonal surfaces (e.g. squares or hexagons), which are arranged in a two-dimensional plane E which corresponds to the screen34. In an embodiment, a starting point for the representation on the screen34is the projection of the measurement points X onto a plane E with a viewer (e.g., eye, camera), at a certain viewpoint V. The projection appears to be in perspective (i.e., the viewpoint V is in the finite) or orthographical (i.e., the viewpoint V in is the infinite). In an embodiment, the projected measurement points X are assigned to single pixels P0, P1, P2. A Z-buffer, which is a two-dimensional array (field) of values for the pixels P. In this Z-buffer, a field element (depth z) is assigned to each pixel P. The depth z of each projected measurement point X corresponds to the distance of the measurement point X to the plane E with respect to the viewpoint V. The field of the pixels P and the Z-buffer may be treated in the same way as the images.

The viewpoint V may be arbitrary per se and is usually changed several times when regarding the scan and/or the scene. In other words, the user may elect to view the measurement point data from a variety of perspectives, with the changes to the displayed measurement points X re-rendered.

Since the measurement points X are punctiform, with gaps in between, and the pixels P usually, in the case of nearby objects O, have a higher density in the plane E than do the projections of the measurement points X, a gap-filling method is carried out to fill as many pixels P as possible for an improved visual representation for the user. In an embodiment, the graphic card32carries out this method by processing the 3-D data following a parallel method described further herein below, the parallel processing method based at least in part on the indication of the viewpoint V and of the plane E.

In an embodiment, initially only those pixels P are filled to which the projection of a measurement point X is assigned, i.e., which exactly cover one measurement point X, such as pixels P0, P1, P2for example. These pixels P are filled with the value of the assigned measurement point X, i.e., brightness (gray-scale value) and, where applicable, color. All other pixels P, which do not exactly correspond with a projection of a measurement point X, i.e., which are “in between” are empty at first, for example are set to a value of zero (e.g. empty or blank). Each of the depths z, i.e., the field elements of the Z-buffer, which are assigned to the initially filled pixels P, is set to that depth z0, z1, z2, which corresponds to the distance of the assigned measurement point X to the plane E. In an embodiment, sometimes referred to as perspective projection, the distance z1 is marked from an object point to a point P1 on a plane E along a line directed to a viewer point V. In this embodiment, the distance z1 is the distance from the object point to point P1. In another embodiment, sometimes referred to as orthographic projection, the distance is a perpendicular distance from the object point to the point P1 rather than along the line aimed toward V.

All other field elements of the Z-buffer (e.g., depths z) are set to a very large value (relative to the scale of the measured points), for example, to approximate an infinite depth. If, when the projection of the measurement points X is made, it turns out that two measurement points X are available for one pixel P, the measurement point having the smaller depth z is selected and the other one is rejected, so that covered surfaces and covered edges, such measurement points XFon the floor ofFIG. 3for example, are not visible.

According to an embodiment, the gap-filling method is performed in dependence on the depth z0, z1, z2, i.e., on the distance to the plane E. The graphic card32selects all pixels P in parallel with respect to time. By way of example, one selected pixel P0is regarded now. The assigned depth z, i.e., field element of the Z-buffer, contains the depth z0. For each selected pixel P0the adjacent pixels P1, P2, are searched consecutively, i.e., alternating between to the left and to the right, and above and below. If the adjacent pixel P1is not yet filled or if its depth z is bigger than the depth z0of the selected pixel P0, it is skipped and the second next pixel P is taken as adjacent pixel P1, if necessary iteratively. If an adjacent pixel P1, the depth z1of which is smaller than the depth z0of the selected pixel P0, is found in one of the directions, a change to the next direction takes place, and it is looked for the adjacent pixel P2(e.g., the depth z2of which is smaller than the depth z0of the selected pixel P0). It is possible to define a maximum number of skipped pixels, i.e., if the adjacent pixel P or P2is not yet found after skipping the maximum number of skipped pixels, the search for P1or P2is aborted. In one embodiment, the search for pixels to fill about an initial pixel P0is limited to those pixels within a radius R of the pixel P0on the two-dimensional pixel array. In another embodiment, the search is also limited by another radius in 3-D coordinates, perpendicular to the viewing direction.

If the adjacent pixels P1and P2to the selected pixel P0have been found in opposite directions, with the depths z1and z2of the adjacent pixels P1and P2being smaller than the depth z0, it is checked whether P1and P2are on the same plane, i.e, whether the amount of the difference of z2and z1is below a threshold value for the depth zcrit, i.e.,
|z2−z1|<zcrit
applies. In such a case, the selected pixel P0is filled with the value which is interpolated between P1and P2, i.e., brightness (gray-scale level) and, if applicable color. The assigned field element of the Z-buffer is likewise set to the interpolated depth between z1and z2. Interpolation weights depend on the distance of the selected pixel P0from P1and P2in plane E.

If the difference of the depths is too big, i.e., the condition
|z2−z1|≧zcrit
applies, it is assumed that P1and P2are located on different planes. The selected pixel P0is then filled with the value, i.e., brightness and, if applicable color, of, for example, the more remote pixel P1or P2, and the assigned field element of the Z-buffer with the bigger depth z1or z2. In another embodiment, the value and the depth of pixel P1or P2having a larger depth z1or z2is transferred or assigned to the other pixel. In the case of more than two adjacent pixels P1, P2, the average value of the majority, i.e., of the adjacent pixels P1, P2, which are located on the same surface, can be transferred.

Selected pixels P0, which are already filled with values of the measurement points, are overwritten by the interpolation of the values of the adjacent pixels P1and P2. In another embodiment, a selected pixel P0, which is already filled, remains unvaried if |z0−z1| is smaller than a threshold, i.e. if P0and P1already belong to the same surface.

If pixels P have been skipped when finding the pixels P1and P2, because they were not filled or because their depth z was too big, their adjacent pixels P1, P2are the same as with the selected pixel P0, so that the skipped pixels PFand the assigned field elements of the Z-buffer, within the framework of the selection taking place in parallel, are likewise filled either with a value which is interpolated between the pixels P1and P2and/or the depths z1and z2(depending on the distance of the selected pixel P0from P1and P2in plane E) or with the value and/or the depth z1or z2of the more remote one among pixels P1or P2(or the average value of the majority) as shown inFIG. 7.

Due to the selection taking place in parallel, filling with the value and/or the depth z1or z2of the more remote among the pixels P1or P2on account of a difference of depths which is too big, leads to the closer-by pixel P1or P2forming an edge. Even if no adjacent pixel P1or P2is found, the depth z1or z2of which is smaller than the depth z0of the selected pixel P0, since the selected pixel P0is at the side of the screen34, an edge is generated, since these selected pixels P0at the edge are not filled then.

Once the pixels along a horizontal row are filled, the same process may be used to fill the vertical gaps between the measurement points P3, P4in a similar manner to that described herein above for the horizontal gap filling. As will be discussed in more detail below, the gap-filling process may be iteratively performed until the image is created.

Gap-filling may take place in the control and evaluation device22or by software running on an external computer. Due to the savings in time by a parallel selection, the hardware-based gap-filling on the graphic card32may be used together with the programming interface of the latter.

Referring now toFIG. 8an embodiment is shown of a method100for acquiring measurement points and displaying the point cloud using gap filling of pixels. The method100begins in block102where the object O is scanned with a metrology device, such as but not limited to a laser scanner10for example. It should be appreciated that the scanned object O may comprise multiple objects, such as the interior rooms and hallways of a building for example. The step of scanning the object O results in the generation of a point cloud representing measured points X on the surfaces of the object O.

The method100then proceeds to block104where it is determined which of the measured points X are visible on the display device30. As discussed herein above the three-dimensional point cloud is projected onto the two-dimensional screen34of display device30to allow the user to view the point cloud. The method then proceeds to block106where the pixels are gap filled to provide the visual appearance of surfaces in the display device30. In an embodiment, the step of gap filling in block106includes a horizontal search to the left of a pixel containing measured point in block108and then a search to the right of the pixel in block110. The step of gap filling in block106further includes the steps of a vertical search above (e.g. towards the top of the display device34) the pixel containing the measured point in block112and then a search below the pixel in block114. In an embodiment, the vertical search of blocks112,114follow the horizontal search of blocks108,110, it should be appreciated, however, that this is for exemplary purposes and the claims should not be so limited. In other embodiments, the vertical search precedes the horizontal search. In an embodiment, the vertical search is performed sequentially with the horizontal search. In another embodiment, the horizontal and vertical searches are performed simultaneously in both directions.

The gap filling steps may be performed for all of the pixels containing a measured point that are being displayed on the display device. In an embodiment, the pixel filling steps are the same as those described herein above with respect toFIGS. 4-7. Once the gap filling is performed, the method100then proceeds to query block116where it is determined whether all of the pixels have been evaluated for gap filling. As will be discussed in more detail below, gaps or empty pixels may occur in some cases where the pixel is not bounded by a pixel containing a measured point or a previously filled pixel. To resolve this issue, the gap filling of block106may be an iterative process. In one embodiment, the process performs for a fixed number of iterations. In another embodiment, the process performs until a stop condition is achieved. In one embodiment, the stop condition is that no additional pixels could be filled in the previous iteration.

When the query block116returns an affirmative, meaning that there are unevaluated pixels, the method loops back to block106. When query block116returns a negative, the method100proceeds to block118where the image is displayed on the display device30.

Referring now toFIGS. 9-11, an embodiment of a method200for the gap filling steps of blocks108-110. It should be appreciated that while method200is described with reference to horizontal gap filling, this is for exemplary purposes and the steps of method200may also be performed for vertical gap filling as well.

The method200begins in block202where a pixel P0is identified. The pixel P0is a pixel that contains an image of the measured point X that is projected from the three-dimensional point cloud onto the two-dimensional display device30. The method200then proceeds to block204where a search is performed of pixels to the left of the pixel P0. As used herein, the terms “left” and “right” indicate opposite sides in the row of pixel P0, this is done for clarity purposes and no intended orientation of the display device34or the point cloud data is intended.

The method200then proceeds to query block206where it is determined if a pixel P1is found within a radius R (FIG. 7). In the exemplary embodiment, the radius R is initially a predetermined value defined by the user, such as five pixels for example. When the query block206returns a negative (no pixel P found), the method200proceeds to block208and no gap filling is performed. When the query block206returns a positive (a pixel P1is found), the method proceeds to block210where a maximum search radius in pixels is determined where the radius is non-proportional or anti-proportional to a distance d1, where the distance d1 is the same as z1 ofFIG. 4. The search is performed in pixel space. It should be appreciated that each pixel may represent a different size in 3D space. For example, if a ray extends through each pixel from the view point into space, the distance between the rays will increase with the distance or depth from the viewpoint (perspective projection). In an embodiment, the search re-projects the pixels into 3D space and objects within a predetermined distance.

The method200then proceeds to query block212where it is determined whether the distance (x0, y0), (x1, y1) is between the measured points of pixels P0, P1. When this distance is not within the radius determined in block210, the query block212returns a negative and proceeds to block214where the direct neighboring pixel P1to the left of (x0, y0) is evaluated in query block216. In query block216, it is determined whether the pixel is non-empty and has a depth less than the depth to the measured point X of P0. When query block216returns a negative, meaning either the pixel is empty or it has a depth greater than the measured point X of P0, the method200loops back to block208. When the query block216returns a positive, the method200proceeds to block218where the values of (x1, y1) and d1 are set to this pixel (e.g. pixel P1). Once the values of block218are set, or when the query block212returns a positive, the method200proceeds to block211(FIG. 10).

In block211, a search is performed of the pixels to the right of the pixel P0. The method then proceeds to query block213where it is determined whether pixel P2 is within the radius R (e.g. 5 pixels). When the query block213returns a negative, the method200proceeds to block208and no gap filling is performed. When the query block213returns a positive, the a maximum search radius is determined in block215that is non-proportional or anti-proportional to the distance d2, where the distance d2 is equivalent to the distance z2 ofFIG. 4. The method200then proceeds to query block217where it is determined if the pixel distance (x0, y0), (x2, y2) is within the radius determined in block215.

When query block217returns a negative, the method200proceeds to block219where the direct neighboring pixel to the right of (x0, y0) is evaluated. This provides for more even gap filling even when the search criteria is not fulfilled. In an embodiment, for directly neighboring pixels, the 3D-criteria is ignored unless better pixels are identified. In query block221, it is determined if the pixel is non-empty and has a depth less than the depth to the measured point X of P0. When query block221returns a negative, meaning either the pixel is empty or it has a depth greater than the measured point X of P0, the method200loops back to block208and no gap filling is performed. When the query block221returns a positive, the method200proceeds to block222where the values of (x2, y2) and d2 are set to this pixel (e.g. pixel P2). Once the values of block222are set, or when the query block217returns a positive, the method200proceeds to block224(FIG. 11).

In query block224, it is determined if the difference between the distances d0 and d1 (e.g. the distance from the viewpoint V to the measured points x0 and x1 ofFIG. 6) is greater than a threshold (e.g. Zcrit). In one embodiment, the threshold is 2.5 centimeters. When query block224returns a negative, indicating that that the measured points already lie on the same plane, the method200proceeds to block208and no gap filling is performed. When query block224returns a positive, the method200proceeds to query block226where it is determined whether the difference between the distances d1 and d2 (e.g. the distance from the viewpoint V to the measured points x1 and x2 ofFIG. 6) is less than a threshold. In one embodiment, the threshold of block226is 10 centimeters.

When query block226returns a positive, meaning the difference in the depths is less than the threshold and that the points lie on the same plane, the method200proceeds to block228where the depth and color of pixels P1 and P2 is interpolated and assigned to the intermediate or intervening pixels. In one embodiment, the depth and color interpolation is weighted with weights (1/r12) and (1/r22), where r1is the distance in pixel units from P1 to P0, and r2is the distance in pixel units from P2 to P0.

When query block226returns a negative, the method200proceeds to query block230where it is determined if the depth d2 is greater than the depth d1. When the query block230returns a positive, the color and depth values from the pixel P2are used for gap filling the empty pixels between pixels P1and P2. When the query block230returns a negative, the color and depth values from the pixel P1are used for gap filling the empty pixels between pixels P1and P2. The purpose of block230is to avoid extending objects by additional pixels at their edges.

It should be appreciated that the method200may be repeated for the vertical gap filling as well.

Turning now toFIGS. 12-16, an example is illustrated of the iteration steps for gap filling, such as provided by query block116(FIG. 8) for example.FIG. 12illustrates the horizontal gap filling that occurs in the first iteration, the blocks with the “x” represent pixels containing a measured point. The number “1” represents empty pixels that are filled in the first iteration, such as by method100for example. Once the horizontal gap filling is completed, the vertical gap filling is performed as shown inFIG. 13. The number “2” represents the pixels filled during the first iteration vertical gap filling. It should be noted empty pixels are only filled when they are bounded on opposite sides by either a pixel having a measurement point X or a previously filled pixel, for example pixel300is filled because it is bounded by the pixels302,304. It should further be noted that once the first iteration is completed, there are a number pixels, such as pixels306,308that have not been evaluated for gap filling because at least one side of the row in which the pixel is located was unbounded at the beginning of the first iteration vertical gap filling.

Referring now toFIG. 14a second gap filling iteration is initiated. The second iteration starts with a horizontal gap filling. In this iteration, the pixel306is evaluated and filled based on the bounding or end pixels310,312. The number “3” represents pixels that were gap filled during the second iteration horizontal gap filling. It should be noted in an embodiment the gap filled pixels have an associated depth and color that was assigned during blocks228,232or234ofFIG. 11. This assigned depth and color allows the intermediate pixels to be evaluated and filled. With the second iteration horizontal gap filling completed, the second iteration vertical gap filling is performed as shown inFIG. 15. Here, the additional pixels are evaluated and filled (where appropriate), based on filled pixels that include those pixels filled during the second iteration horizontal gap filling. For example, pixel308is evaluated and filled based on end pixels306(filled in the second iteration horizontal gap filling) and pixel312(filled in the first iteration gap filling).

In the illustrated embodiment, when the second iteration vertical gap filling is completed, there remain no unevaluated bounded pixels. Therefore, the query block116would return a negative and the method100would proceed with displaying the image on the display device34. It should be appreciated that in other embodiments, more or less iterations may be performed.

It should be appreciated that while embodiments herein describe the creation of a displayed image by a gap-filling process with respect to data acquired by a laser scanning device, this is for exemplary purposes and the claims should not be so limited. In other embodiments, the displayed image may be created using point cloud data generated by any metrology device, such as a triangulation-type laser scanner device, a triangulation-type structured light scanner device, or a time-of-flight based scanner device for example.