A 455Kb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE
"Good!" Step. Step. Step. Plumb the pole. Beep . . . beep . . . beep. "Good!" So goes the familiar rhythm of any one of a thousand topographic surveys on any given day.
Each month, surveying magazines are filled with images of point clouds from laser scans. And each month the average practicing surveyor (those running one to three crews) knows that like topographic surveys, laser scanning is drawing closer to becoming a mainstream reality. At this point in time, three factors continue to dissuade the common surveyor from investing in laser scanning: implementation, cost/return of investment, and complexity.
How to implement laser scanning technology to your work flow is the paramount issue, and one that is beyond the scope of this humble article. Flip through a few pages of any surveying magazine from the past 10 years and you will find numerous creative examples for implementation: architectural design, civil design, facility mapping, monitoring for subsidence, reverse engineering, and computer graphics for entertainment.
Return of investment is improving. Not too long ago, a full set up (scanner, software, computer, accessories) might cost a quarter of a million dollars. Today, depending on the manufacturer, that figure is less than one hundred thousand dollars, with a lot more capability than earlier models.
Complexity is also diminishing substantially. The many varied point clouds appearing monthly in glossy magazines make beautiful eye candy, but their real world application is another story. How does a surveyor relate the size and location of a building to the architect who will be designing the addition to the building amongst the 28 million points in the point cloud? Without the ability to harvest from those point clouds meaningful data that can then be correlated to a simplified map for use by the client, the scans are simply an attractive image.
Laser scanning creates a virtual world within which the surveyor works. Once scans are complete, the surveyor selects specific points within the cloud to be placed in the survey plat that are necessary for the project at hand.
This is the philosophy behind MicroSurvey CAD Ultimate. With a price tag of only $3,495, Ultimate goes a long way toward making the ROI in laser scanning easier to achieve. With a significant portion of the surveying community using MicroSurvey products (office and field software) their point cloud product exploits a familiar user interface that reduces the difficulty of working with point cloud data.
MicroSurvey CAD 2010 works inside IntelliCAD version 6.5 (version 7 is still considered "beta" by the IntelliCAD consortium at the writing of this article). Because the graphics capability of IntelliCAD is not equipped to handle the large volume of points in a typical scanned point cloud, the point cloud utility runs simultaneously with MS CAD and runs within its own window. Before you start thinking that this is a deficiency in IntelliCAD that AutoCAD doesn’t suffer from, keep in mind that only with the most recent version of AutoCAD (version 2011) can it handle the large amounts of data in a point cloud.
By clicking the "MS Tools" drop down from within MS CAD, the third option from the top is a simple looking option labeled "Point Cloud". Selecting this option opens a separate window for the PointCloud utility. Once open, Ultimate prompts the user to open a point cloud file. MicroSurvey states in its product information that the point cloud utility was developed in cooperation with Leica Geosystems, a major developer of laser scanning hardware and software. The list of compatible file types would seem to confirm this. Leica PCS (FastScan), PTS (ASCII Unordered Interchange Format), PCG (Point Cloud Group), PCSX, PCST, PCI, PCIT and LAS (LIDAR) are all supported file types.
Once the file is open, Ultimate allows for quick three-dimensional rotating, panning, and zooming of point clouds. There are two different modes in the point cloud utility: View Mode and Draw Mode, which change the action of the cursor. The view can still be manipulated while in Draw Mode (such as panning and rotating). Using the stick pin feature the user can select a point in the cloud for the center of rotation. For this review, I loaded the software on a Toshiba laptop with 4 gigabytes of RAM, an Intel i7 Quad Core processor running 1.73 gigahertz and an NVIDIA graphics card. At around a thousand dollars, this system proved to be very capable at driving Ultimate, and showed that you don’t need to have a multi-thousand dollar computer system to operate the softwarea significant cost savings over the cost of a capable computer system just a few years ago. I was able to pan, rotate and zoom an aerial LiDAR scan containing 409,000 points with no skipping, jumping or flickering of point data. The point cloud engine was extremely efficient even with such large data sets.
Automatically filtering scan data can make a tremendous difference in productivity. One of the incredible tools available is the grid survey tool found in the reference plane toolbox. The user can select the lowest point within a specified grid interval using this tool. With a site dotted with trees and carpeted with high grass, this routine allows the user to get to the ground, or at least the shots closest to the ground, within a user-defined square interval. Those points can then be exported to the MicroSurvey CAD environment for further manipulation.
Another automated feature is the road line extraction. One application that laser scanning is finding a quick home in is roadway scanning. High volume traffic, hazardous working conditions, mostly open sites, and the need for rapid collection of data all make highway mapping ideal for laser scanning, particularly mobile scanning. The automatic road line extraction ingeniously uses the contrasting color of the pavement and road striping to automatically draw lines along the paint. This can then be quickly exported to the CAD side for surface modeling or mapping.
Because data gathering is so quick in the field with laser scanning, often a user will choose to allow the scanner to scan its full 360-degree range at each setup on the presumption that the additional data may be useful sometime in the future. While that may be good for the future, it compels the user to do some data selection back at the office. The point cloud environment has a wonderful box selection method for selecting points within a very specific user-defined area that can then be exported back to the CAD environment.
Specific points can be selected and sent to CAD as well. This capability is perhaps the most similar to surveying in a virtual world. Imported points from the point cloud window to the CAD window can then be given a point number and description (again, just like surveying in the field). Lines, polylines (two- and three-dimensional, optionally) and circles and arcs can be drawn in the point cloud window and then be exported to the CAD window also.
While Ultimate does not support animation development, MicroSurvey offers a product called PointCloud CAD which fills that gap; a benefit for developing presentations, such as project proposals and crime scene investigation.
I was impressed with the surface modeling tools available. With the Draw Mode selected, using the line drafting tools, breaklines can be drawn and exported. Points can then be exported. Within the CAD environment a surface can then be drawn just as though it were collected in the field. The system works the way a surveyor is already a
ccustomed to working, reducing the complexity of getting from a point cloud to a finished product.
One tool that appears to be missing is a registration tool. Multiple scans (think of multiple individual total station set-ups) have to be stitched together in a separate utility. If this option were available, this would more likely be a one-stop software solution.
It was great working with data gathered from a terrestrial setup, then from aerial LiDAR data, and then from mobile scan data. The flexibility is fantastic. The speed of the point cloud utility was incredible. From loading large data sets, to manipulating the views, to exporting data, I never had to wait for the software to catch up with my commands. The utility ran smoothly and quickly, partly due to my fast computer and, no doubt, also due to the apparently efficient software.
Once the necessary data from the voluminous point cloud is imported into MicroSurvey CAD, the full featured CAD environment offers a wide array of routines and tools for making a map that can then be used for producing a map that can then be used by design professionals.
MicroSurvey CAD Ultimate, while still rather new, is very capable software and puts point cloud tools within easy reach and in a familiar and mature survey software. The point cloud engine has been in service for quite a while in other products, and is fairly mature as well. The blending with a dedicated survey software reduces the learning curve (which improves the bottom line), costs well under five figures, and allows the user to get from a pretty picture to a real working drawing in short order.
If you are working with point clouds and are looking for a way to get meaningful survey drawings, or if you are occasionally given point clouds for viewing, MicroSurvey is certainly worth a look. With a free 30-day demo, you can try it for yourself for the cost of a quick Internet connection.
Shawn Billings is a licensed land surveyor in East Texas and works for Billings Surveying and Mapping Company, which was established in 1983 by his father, J. D. Billings. Together they perform surveys for boundary retracement, sewer and water infrastructure routes, and land development.
A 455Kb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE