I have a point cloud of a terrestrial laser scan of some surfaces. I also took topo shots on 7 profiles about every 10 feet, about 10 shots per line. One section is C/L of a road, the others are steep grass slopes.
What I would like to do is get a listing of of how far above or below the DTM created from the point cloud data each topo shot is.
Or, alternatively, to cut a section through the point cloud data and compare the two lines (i.e. field surveyed and extracted).
Any ideas on what software could do this?
I think the ideal would be to have the dtm loaded, and import a point file (N,E), where it would then interpolate the elevation of each N,E from the dtm, and output a report.
The same situation should apply to LIDAR data. I have supplied check points to LIDAR collection companies, and they somehow spit out a comparision of the points versus the LIDAR data.
Coordinate Geometry module of Bentley Geopak. I suppose Inroads does it as well but I don't use it. In tool bar choose Element/Point/Compare Points to TIN.
Example output
JOB File: C:SurveyProjects675job675.gpk
TIN File: C:SurveyProjects675675.TIN
Point Feature COGO Elevation TIN Elevation Elev Diff Location
======================================================================
12125 C9002 911.92 912.07 -0.14 BELOW***
12126 C9002 911.72 911.86 -0.15 BELOW***
12127 C9002 911.49 911.65 -0.17 BELOW***
12128 C9002 911.29 911.45 -0.16 BELOW***
12129 C9002 911.10 911.26 -0.15 BELOW***
12130 C9002 910.98 911.11 -0.14 BELOW***
12131 C9002 910.84 910.96 -0.12 BELOW***
12132 C9002 910.73 910.87 -0.14 BELOW***
12133 C9002 910.56 910.70 -0.14 BELOW***
12134 C9002 910.69 910.71 -0.02 BELOW
12135 C9002 910.51 910.54 -0.03 BELOW
12136 C9002 910.41 910.40 0.00 EQUAL
12137 C9002 910.25 910.24 0.01 ABOVE
12138 C9002 910.09 910.09 0.00 EQUAL
12139 C9002 909.90 909.97 -0.07 BELOW*
12142 C9002 909.44 909.58 -0.14 BELOW***
12143 C9002 909.33 909.40 -0.08 BELOW*
12144 C9002 909.25 909.32 -0.06 BELOW*
12145 C9002 909.16 909.26 -0.09 BELOW*
12146 C9002 909.11 909.31 -0.20 BELOW***
12147 C9002 909.05 909.18 -0.14 BELOW***
12148 C9002 909.00 909.05 -0.06 BELOW*
12149 C9002 908.95 908.99 -0.04 BELOW
12150 C9002 908.91 908.93 -0.02 BELOW
12151 C9002 908.82 908.87 -0.05 BELOW*
12152 C9002 908.74 908.81 -0.06 BELOW*
12153 C9002 908.67 908.73 -0.06 BELOW*
12154 C9002 908.60 908.65 -0.05 BELOW*
12155 C9002 908.55 908.58 -0.03 BELOW
12156 C9002 908.47 908.50 -0.03 BELOW
12157 C9002 908.32 908.40 -0.08 BELOW*
12158 C9002 908.28 908.35 -0.07 BELOW*
12159 C9002 908.68 908.71 -0.04 BELOW
12160 C9002 908.60 908.63 -0.03 BELOW
12161 C9002 908.52 908.55 -0.03 BELOW
12162 C9002 908.45 908.47 -0.02 BELOW
12163 C9002 908.37 908.41 -0.04 BELOW
12164 C9002 908.30 908.34 -0.04 BELOW
12165 C9002 908.24 908.28 -0.04 BELOW
12166 C9002 908.19 908.22 -0.03 BELOW
12167 C9002 908.15 908.17 -0.02 BELOW
12168 C9002 908.11 908.12 -0.01 BELOW
12169 C9002 908.09 908.08 0.01 ABOVE
12170 C9002 908.08 908.07 0.01 ABOVE
12171 C9002 908.05 908.06 -0.01 BELOW
12172 C9002 908.05 908.04 0.00 EQUAL
12173 C9002 908.04 908.01 0.03 ABOVE
12174 C9002 908.03 907.99 0.04 ABOVE
12183 C9002 907.67 907.66 0.00 EQUAL
12184 C9002 907.60 907.62 -0.02 BELOW
12185 C9002 907.51 907.54 -0.04 BELOW
12186 C9002 907.43 907.44 -0.01 BELOW
12187 C9002 907.36 907.34 0.02 ABOVE
12188 C9002 907.22 907.24 -0.02 BELOW
12189 C9002 907.05 907.13 -0.08 BELOW*
12190 C9002 906.87 906.98 -0.11 BELOW***
12191 C9002 906.80 906.84 -0.05 BELOW
12192 C9002 906.63 906.68 -0.05 BELOW*
12193 C9002 906.48 906.53 -0.05 BELOW*
12194 C9002 906.38 906.38 0.00 EQUAL
12195 C9002 906.25 906.26 -0.01 BELOW
12196 C9002 906.11 906.12 -0.01 BELOW
12197 C9002 905.97 905.98 -0.01 BELOW
12198 C9002 905.84 905.87 -0.03 BELOW
12199 C9002 905.71 905.75 -0.04 BELOW
12200 C9002 905.58 905.61 -0.03 BELOW
12201 C9002 905.44 905.47 -0.03 BELOW
12202 C9002 905.28 905.34 -0.05 BELOW*
12203 C9002 905.12 905.18 -0.06 BELOW*
12204 C9002 904.96 905.00 -0.03 BELOW
12205 C9002 904.77 904.84 -0.07 BELOW*
12206 C9002 904.64 904.68 -0.05 BELOW
12207 C9002 904.53 904.55 -0.03 BELOW
12208 C9002 904.39 904.42 -0.03 BELOW
12209 C9002 904.24 904.26 -0.02 BELOW
12210 C9002 904.06 904.11 -0.05 BELOW
12211 C9002 903.89 903.96 -0.06 BELOW*
12212 C9002 903.73 903.81 -0.09 BELOW*
12213 C9002 903.62 903.66 -0.05 BELOW
12214 C9002 903.48 903.51 -0.04 BELOW
12215 C9002 903.36 903.37 -0.01 BELOW
12216 C9002 903.23 903.26 -0.03 BELOW
12217 C9002 903.13 903.16 -0.03 BELOW
12218 C9002 903.03 903.06 -0.03 BELOW
12219 C9002 902.95 902.98 -0.03 BELOW
12220 C9002 902.88 902.91 -0.03 BELOW
12221 C9002 902.79 902.88 -0.09 BELOW*
12222 C9002 902.79 902.85 -0.06 BELOW*
12223 C9002 902.76 902.82 -0.06 BELOW*
12224 C9002 902.76 902.79 -0.03 BELOW
12225 C9002 902.72 902.77 -0.05 BELOW
12226 C9002 902.73 902.76 -0.04 BELOW
12227 C9002 902.69 902.75 -0.06 BELOW*
12228 C9002 902.72 902.74 -0.02 BELOW
12229 C9002 902.73 902.74 -0.02 BELOW
12230 C9002 902.78 902.75 0.03 ABOVE
12231 C9002 902.78 902.83 -0.05 BELOW*
12232 C9002 902.82 902.89 -0.08 BELOW*
12233 C9002 902.90 902.95 -0.05 BELOW
12234 C9002 903.01 903.01 0.01 ABOVE
12235 C9002 903.11 903.08 0.03 ABOVE
12236 C9002 903.15 903.15 0.00 EQUAL
12237 C9003 902.75 902.74 0.02 ABOVE
12238 C9003 902.57 902.56 0.01 ABOVE
12239 C9003 902.42 902.37 0.05 ABOVE*
12240 C9003 902.30 902.20 0.11 ABOVE***
12241 C9003 902.16 902.16 0.00 EQUAL
12242 C9003 902.19 902.13 0.06 ABOVE*
12243 C9003 902.26 902.30 -0.04 BELOW
12244 C9003 902.47 902.47 0.00 EQUAL
12245 C9003 902.75 902.74 0.01 ABOVE
12246 C9003 903.07 903.03 0.03 ABOVE
12247 C9003 903.38 903.34 0.04 ABOVE
12248 C9003 903.67 903.67 -0.01 BELOW
12251 C9003 904.33 904.34 -0.02 BELOW
12252 C9003 904.47 904.52 -0.04 BELOW
============
The Sum of (Elev Diff)Squared = 0.48
The Ave of (Elev Diff)Squared = 0.00
The Root Mean Square Error is = 0.06
National Standard for Spatial Data Accuracy(NSSDA) is = 0.13
Points PASS the 95% confidence test based on 1.96 Chi Square Value.
I found a way to do it in Global Mapper., I import the xyz point cloud as an elevation grid, which it then creates a dtm from. Then I import the points that I surveyed, select them with the digitizer tool (edit...select all features with digitizer tool), and right click to get a function "Apply Elevations from Terrain Layers to Selected Feature(s)". GM then replaces the elevation attribute for all of the points I selected with the DTM derived value. I then file...export vector format...csv and I have a file that has the points with the dtm values. I load them into excel along with the original file, and I can see the differences.
It would be nice if it kept the old elevation as an attribute.
Seems like this should be easy to do in Trimble Real Works software, but it isn't. At least it is not readily apparent.
