# Error in GCP and densified point cloud

**URL:** <https://community.pix4d.com/t/error-in-gcp-and-densified-point-cloud/2893>\
**Category:** PIX4Dmapper Questions/Troubleshooting\
**Created:** [February 9, 2017, 6:53pm UTC](https://community.pix4d.com/t/error-in-gcp-and-densified-point-cloud/2893 "2017-02-09T18:53:23Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Jamey\_Gray](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/jamey_gray/32/216_2.png) [@Jamey\_Gray](https://community.pix4d.com/u/Jamey_Gray)\
**Post date:** [February 9, 2017, 6:53pm UTC](https://community.pix4d.com/t/error-in-gcp-and-densified-point-cloud/2893/1 "2017-02-09T18:53:23Z")

</div>

I have a number of GCP’s reporting with low relative error. The problem I’m seeing is showing well in the screenshot. The densified point cloud is significantly offset from the initial/calculated GCP position. I believe there is a mistake in my process but unsure where to start at this time. The point shown below is calculated to be at an elevation of 3172.992’. The closest point in the densified point cloud is 3173.63’.

The other side of this issue is all my GCP’s are reporting with an acceptable RMS and Sigma while most of the check points I have are too far out of tolerance to even be included in the report.

I’ve added manual tie points and although it seems to improve the reporting I’m still not please with the difference between and manually marked point and the calculated point.&nbsp;

---

<div class="post-metadata">

**Author:** ![nikoleta.guetcheva](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/nikoleta.guetcheva/32/187_2.png) [@nikoleta.guetcheva](https://community.pix4d.com/u/nikoleta.guetcheva)\
**Post date:** [March 6, 2017, 1:10pm UTC](https://community.pix4d.com/t/error-in-gcp-and-densified-point-cloud/2893/2 "2017-03-06T13:10:47Z")

</div>

Dear Dustin,

This is an interesting issue that is difficult to analyze and investigate without looking at the quality report, the images or even process locally. Could you please share the quality report, the images and the p4d file with us in order to further investigate?

You can upload the images and the p4d file to our Cloud following [these](https://support.pix4d.com/hc/en-us/articles/202558589-Uploading-Projects-Files-on-Pix4D-Cloud)&nbsp;instructions.&nbsp;

You can also send us the Quality Report in a request that you can submit&nbsp;[here](https://community.pix4d.com/hc/en-us/requests/new#gsc.tab=0).&nbsp;

Best regards,

---

<div class="post-metadata">

**Author:** ![Derrek\_Yates](https://avatars.discourse-cdn.com/v4/letter/d/5f9b8f/32.png) [@Derrek\_Yates](https://community.pix4d.com/u/Derrek_Yates)\
**Post date:** [October 11, 2018, 2:13pm UTC](https://community.pix4d.com/t/error-in-gcp-and-densified-point-cloud/2893/3 "2018-10-11T14:13:23Z")

</div>

I am having this same problem, any solutions ?

---

<div class="post-metadata">

**Author:** ![Blaz](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/blaz/32/4344_2.png) [@Blaz](https://community.pix4d.com/u/Blaz)\
**Post date:** [October 12, 2018, 7:46am UTC](https://community.pix4d.com/t/error-in-gcp-and-densified-point-cloud/2893/4 "2018-10-12T07:46:59Z")

</div>

@Derrek, could you give a more detailed description of the issue you are facing:

- Which version are you using (e.g. 4.3.27)?&nbsp;
- Can you see the shift in the rayCloud? Could you share some screenshots with us?
- Is the shift only vertical or also horizontal?
- Does [reoptimizing](https://support.pix4d.com/hc/en-us/articles/202557809-Menu-Process-Reoptimize) the project solve the issue?

Best,