# Local Coordinate transform

**URL:** <https://community.pix4d.com/t/local-coordinate-transform/6193>\
**Category:** PIX4Dmapper Questions/Troubleshooting\
**Created:** [March 13, 2018, 6:35pm UTC](https://community.pix4d.com/t/local-coordinate-transform/6193 "2018-03-13T18:35:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Ryan\_Sorensen](https://avatars.discourse-cdn.com/v4/letter/r/d26b3c/32.png) [@Ryan\_Sorensen](https://community.pix4d.com/u/Ryan_Sorensen)\
**Post date:** [March 13, 2018, 6:35pm UTC](https://community.pix4d.com/t/local-coordinate-transform/6193/1 "2018-03-13T18:35:07Z")

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Hello,

I’m trying to export the LAS point cloud to Civil 3D but the output coordinate system from Pix4D is not where I’m expecting it to be.&nbsp; The local coordinate system from the planset is:

Northing Conversion:&nbsp;2624946.571 (local to state plane)

Easting Conversion:&nbsp;1312508.894 (local to state plane)

Scale: 0.999899046

&nbsp;

When I use those factors and adjust my GCP they line up where I expect them to on the Pix4d map and I’m able to use the basic GCP editor.&nbsp; Since the drone captures everything in state plane this is all fine and well for the processing.&nbsp; My problem is the output of the LAS, I manually enter them into the site calibration in Pix4d but the results don’t make sense. &nbsp;

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I use the following in the site calibration:

Northing Conversion: -2624946.571 (difference from state plane to local)

Easting Conversion: -1312508.894 (difference from state plane to local)

Scale: 1.000100964 (inverse from original scale)

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I’m sure I have made a mistake somewhere since the point clouds are not falling within my project in Civil 3D.&nbsp; Any help would be appreciated. &nbsp;

&nbsp;

-Ryan

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<div class="post-metadata">

**Author:** ![Ryan\_Sorensen](https://avatars.discourse-cdn.com/v4/letter/r/d26b3c/32.png) [@Ryan\_Sorensen](https://community.pix4d.com/u/Ryan_Sorensen)\
**Post date:** [March 13, 2018, 7:02pm UTC](https://community.pix4d.com/t/local-coordinate-transform/6193/2 "2018-03-13T19:02:17Z")

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Found the problem, going back from state plane to local requires the inverse scale to be multiplied then the Transform be added/subtracted.&nbsp; I imagine Pix4d assumes

(State Plane Northing or Easting + Northing or Easting Transform)\*Scale=Local Coordinates, This is what I use for the GCP while processing.

but to transform back to local from state plane I need

(Local Coordinates\*inverse scale)-Northing/Easting Transform, so I can import the LAS into Civil 3D.

I suppose the fix is the edit the EXIF data in the drone photos and convert them to local coordinates prior and ignore the map coordinates in pix4d while processing.

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