Elevation Difference in Civil 3d

PIX4Dmapper
1

Hello,

Im getting some inconsistencies on my pix4d surface when I import it as a shape file to civil 3d compared to ground topo that was shot in the field.

There is roughly a .2 error across the site, however, there is a corner the site where the error is over 2 feet.

I have tried adding GCP’s in the area, removing GCP’s but nothing seems to bring the surface down to match the rest of the surface.

I have reprocessed multiple times and verified that the field data is correct.
Southern Sky V2_report.pdf (2.7 MB)

2

Hi @msmith,

Thanks for sharing the quality report with us.

I noticed that the vertical coordinate system of the images is set to EGM96, can you change it to Ellipsoidal?
Another suggestion is to process with 1/2 Image scale. May I ask if the problem is on the vertical or the horizontal?

Best,

3

-What is the coordinate system assigned to the Civil3D project? (command: CSASSIGN)

-Is the .2 consistent accross the whole project, other than the corner that’s 2 ft off?

-Do you have a .prj file for the field data? Most surveyors that I work with are using NAD83(2011). I noticed that yours is set to just NAD83. The .prj should also include the vertical coordinate system that survey used. That could be part of the issue.

There are programs (I use Global Mapper) that allow you to adjust the elevation of an entire dataset by whatever you want. Let me know if I can help with that in any way.

4

I appreciate everyones help.

We flew the site again at 345 instead of 400 and increase overlap with an RTK drone and that tightened up the surface.

Thank you