topic compare 3d polyline to raster surface in Geoprocessing Questions

compare 3d polyline to raster surface

forestknutsen1 — Fri, 30 Dec 2016 01:40:26 GMT

I have 3D flight path data. I want to know if the aircraft is violating above ground altitude restrictions over sensitive areas. I have a raster mosaic of national elevation data for the areas of interest. I was originally thinking that I could turn the line into a raster with the cell values containing the interpolated z values along the line (Looks like arc can not do this out of the box? ). Then I could do map algebra to compare the two surfaces. If the difference between the two surfaces is below the min above ground recommendation the flight will be flagged for investigation. Now I am thinking of using densify on the line turning it into points and comparing them to an extraction by point from the ground raster.

I am sure I am not the first person to want to do this. Does anyone have any good suggestions for this problem? I have thousands of flights to process for the next few years so I will be scripting the solution.

Thanks,

Forest

Re: compare 3d polyline to raster surface

MervynLotter — Fri, 30 Dec 2016 05:13:26 GMT

If the source data is in point format, you could use the Extract Values to Points tool to add the elevation value from your raster to your point dataset. Then simply add a column and use the calculator to subtract the two values. This would introduce less 'noise' through interpolation, particularly relevant if it may trigger an investigation.

Re: compare 3d polyline to raster surface

forestknutsen1 — Fri, 30 Dec 2016 19:26:48 GMT

Yes, I agree with that overall. The raw data is lat, long, altitude locations. But I do need to add vertices because the time between sample points is too great. The aircraft can transit a restricted area without collecting a GPS point.

I think I am going to go with:

Densify

Feature Vertices to Points

Add XY Coordinates

Extract Values to Points

Calculate Field

Then based on this output I can select points and buffer then cut my original lines to show problem areas of the flight.