# Large Error on Linear Project

**URL:** <https://community.pix4d.com/t/large-error-on-linear-project/8366>\
**Category:** PIX4Dmapper Questions/Troubleshooting\
**Created:** [May 20, 2019, 12:29pm UTC](https://community.pix4d.com/t/large-error-on-linear-project/8366 "2019-05-20T12:29:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![James\_Hanley](https://avatars.discourse-cdn.com/v4/letter/j/4491bb/32.png) [@James\_Hanley](https://community.pix4d.com/u/James_Hanley)\
**Post date:** [May 20, 2019, 12:29pm UTC](https://community.pix4d.com/t/large-error-on-linear-project/8366/1 "2019-05-20T12:29:46Z")

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Hello:

&nbsp;

I’ve been using Pix4D for a few years and am very familiar with the software.&nbsp; We recently flew +/- 1200-LF of roadway at 60-M in elevation at 5-MPS w/ +/- 90% overlap.&nbsp; Generally we get very good results with these specs.&nbsp; However, for some reason the vertical error is significant.&nbsp; See attached Quality Report.

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Does anyone see anything in the report that may indicate why the error is so high?&nbsp; Thank you for your help.

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- Jim

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**Author:** ![Daniel\_Rico\_Cordero](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/daniel_rico_cordero/32/187_2.png) [@Daniel\_Rico\_Cordero](https://community.pix4d.com/u/Daniel_Rico_Cordero)\
**Post date:** [May 21, 2019, 1:23pm UTC](https://community.pix4d.com/t/large-error-on-linear-project/8366/2 "2019-05-21T13:23:05Z")

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Hello James,

I cannot see the Quality Report, I suppose there was an error when uploading it.

Would you please send it again?

If you prefer, you can open a support ticket where it is easier to exchange files and projects.

Thank you very much.

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**Author:** ![James\_Hanley](https://avatars.discourse-cdn.com/v4/letter/j/4491bb/32.png) [@James\_Hanley](https://community.pix4d.com/u/James_Hanley)\
**Post date:** [May 21, 2019, 2:42pm UTC](https://community.pix4d.com/t/large-error-on-linear-project/8366/3 "2019-05-21T14:42:36Z")

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I realized that but I can’t load a PDF?&nbsp; Anyway - here are a series of jpg of the QR.&nbsp; Thank you for reviewing.

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**Author:** ![Daniel\_Rico\_Cordero](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/daniel_rico_cordero/32/187_2.png) [@Daniel\_Rico\_Cordero](https://community.pix4d.com/u/Daniel_Rico_Cordero)\
**Post date:** [May 22, 2019, 6:39am UTC](https://community.pix4d.com/t/large-error-on-linear-project/8366/4 "2019-05-22T06:39:34Z")

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Hello again,

Thanks for the feedback.

By looking at the Quality Report:

- I would change the GCPs accuracy which is set to 0.02 ft. I would use at least 0.06 as you have done with the last GCP.

- GCP 3015 has a high error. I would review the marks just in case there was a mistake. As it is a GCP, it is used in the adjustment and in case it is wrong it might be the cause of the large errors in the checkpoints.

- I am not sure what was the speed of the drone but I would try to apply the rolling shutter correction too.

- What is the accuracy of the geotags?

Please let me know how it goes.

Regards.

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