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Model in feet, imports in Meters

Hello, I am running into a problem and I was hoping for some insight as to what is happening and how to fix it.

Before I begin, I am working with project data processed in Pix4d desktop, I completed this project a few months ago and the final product included traditional survey data along with UAS data from my M600P/Sony A7rii, all residing in AutoCad Civil3d 2019.

In this first photo you can see the XY values of a point in the Pix4d Survey model match the XY values of the same point in the traditional survey data. Confirming the coordinate systems and units are correct.

Upon importing the linework from Pix4d Survey into Civil3d 2019 I can see there is a meters conversion occurring. Initially I disregarded but when the linework was loaded It was clearly not in the correct location.

Location of DXF vs Traditional survey data.

After opening the DXF and searching for the $insunits section I discovered the DXF insertion units are being written in meters despite the civil3d .DWG, Pix4d desktop and Pix4d Survey data all showing the correct units, feet. How can I change the units when exporting? Manually editing the $insunits field to the correct value of <2> does not work and I did not see any settings for this in Pix4d Survey.

Finally, the last picture shows that the data from the DXF is being scaled by the conversion factor of 3.281. (the correct Z)(3.281)=4718.72’

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@dustin_shropshire, thank you for attending the webinar yesterday! I hope you got more information on how to use Pix4Dsurvey.

Your observation is correct, INSUNITS in the exported DXF is always set to meters. It should match the value of the units in the coordinate system if CS units are, for example, in foot, US survey foot, or meters.

The team is looking into it in order to fix this behavior. In the meantime, we recommend you to

  • Change INSUNITS in the .dxf to 2.
  • Use insert instead of opening the file.
  • Use the origin of 0.0, and the scale of 1 in X and Y.
  • Explode the imported geometries.

Let us know how it goes,

I’m having this same problem. I insert it as a block like in the directions above, it converts back to feet but they X 3.2808 higher. The block is defined in meters when it is exported from Pix4Dsurvey.

ANY UPDATE ON THIS

Hi @gsteinhilber1,

When you changed the INSUNITS did you try opening the DXF in a text editor before opening in CAD? When I do it that way, everything else falls into place at the right size. Longer term, we’re working on properly handling units so that isn’t necessary.

thanks,
Nate

Hi all,

We release a new Pix4Dsurvey version 1.1.1 that contains improved.dfx export: INSUNITS value in the exported .dxf match the units of the Pix4Dsurvey project.

For example, when exporting a .dfx file from a project in feet, the .dxf imported into Autodesk products will be correctly imported in feet.

For values that are not on the list of possible INSUNITS values (table), the INSUNITS value is set to 0. In this case we recommend to:

  • Change INSUNITS in the .dxf to a preferred value.
  • Use insert instead of opening the file.
  • Use the origin of 0.0, and the scale of 1 in X and Y.
  • Explode the imported geometries

Best,

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