Issue link: https://read.dmtmag.com/i/53167
but, when in the field, the points varied depending on terrain. The second test of LIDAR data demonstrated this when a point generated from the GIS placed it on top of a large rock. Because of the nature of the LIDAR raster, the field measurement was much higher than the GIS due to the averaging of pixel size. Figure 1 is the resulting map, which was used to show DOT members how the data preformed. The next project was the exact opposite. Making Progress The LIDAR data were used as the preliminary survey, and then the surveyor checked the points in the field. It also showed the same results, which gave DOT and their surveyors confidence in its value. The data then were used to create hydrographs of the area used to estimate flow values of the creek below. The bridge- repair project also included rerouting a stream through a wider channel to reduce some of the flooding issues previously recorded in this area. The next problem was getting the data to surveyors, who were using CAD systems, so they could work with them. This was much more difficult than anticipated due to the size of the point files and the ability to use raster datasets as elevations. The projects at this stage started off with the consultant or surveyor wanting all the data for their region. The chosen area was only a few square miles, but there were far too many points for their software, so the contours were clipped out. The default two-foot contours created by IAGT were good for most projects, but because of the differences in drawing ability of CAD and GIS software, it could be too much. Working with consultants, the request changed from "all the data" to "what did they need to finish the project." Therefore, the first custom LIDAR tool created was a simple clip-and-contour tool to create a raster and contour model for any area in the county at any interval. The tool was created in ArcGIS Model Builder and used different tools from 3-D Analyst. The tool starts off with a simple polygon of the area of interest, which must contain a value of 1 some- where in the attribute table. This allows for the next step, a Boolean clip, to multiply the complete elevation raster by the clipped area. Contours then are created at any interval from the clipped elevation model. Figure 2 shows the complete model in Model Builder, and a python script also was created. Both versions of this tool then were added to a common toolbox on ArcGIS Server and can be accessed by any of the GIS staff. This model helped some projects, but other projects required more detail on the part of the surveyor. Fine Tuning After contours could be extracted, the next need was for transects. Surveyors use transects at different intervals to create flow models for different features. These transects are created using the terrain as a base, and they stretch outside the channel to get a good picture of the entire area. The second tool took the points that the surveyor wanted to use and assigned z values. This gave the surveyor staff control over which points were col- lected and gave them the ability to add more points if needed during a project. These transects can be converted to a 3-D feature using LIDAR data and the terrain model created in ArcGIS, but only a GIS can read the information. After some experimenting and going back and forth between the GIS and the surveyor's system, another tool was created. This tool used the transect and points that the surveyor team wanted to look at to create the x,y,z table needed for the surveyor's model- ing software. This tool was another simple solution to a prob- lem. It created a point Shapefile from an Excel table and then interpolated it to 3-D. Then, using a VB script (later replaced in ArcGIS 10 as Calculate Z Value), it calculated the z value into the table. Figure 3 shows the model and an example of its results. The points can be symbolized for a top-down view of the elevations. Figure 2. A complete model of the area was created in Model Builder. 16 GEO WO RLD /JANUAR Y 2O12 Trimming Time and Costs These tools, combined with the LIDAR data, assisted in the preplanning stages of several projects. The overall time savings in the early stages of a project are Imagery/LIDAR Special Issue LIDAR Applications