# GCP's floating in the air

**URL:** <https://community.pix4d.com/t/gcps-floating-in-the-air/5494>\
**Category:** PIX4Dmapper Questions/Troubleshooting\
**Created:** [August 16, 2016, 8:40pm UTC](https://community.pix4d.com/t/gcps-floating-in-the-air/5494 "2016-08-16T20:40:07Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![rogelio\_flroes](https://avatars.discourse-cdn.com/v4/letter/r/d78d45/32.png) [@rogelio\_flroes](https://community.pix4d.com/u/rogelio_flroes)\
**Post date:** [August 16, 2016, 8:40pm UTC](https://community.pix4d.com/t/gcps-floating-in-the-air/5494/1 "2016-08-16T20:40:07Z")

</div>

&nbsp;Hello,

&nbsp;

this is my first time using Pix4D. Here it is what I been doing and what I want to accomplish:

I took images with a Phantom 4. I took 5 GCP with a high accuracy GPS unit. After step 1. Initial Processing I add the GCP into the software. I get the following results:

my points are way higher than my point cloud. I am thinking it has to be with the coordinate systems but I am not sure about it. This area is located in northern California coordinates&nbsp;( State Plane Zone 3). Can someone point me in the right direction? Thanks in advance

---

<div class="post-metadata">

**Author:** ![Fay\_king](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/fay_king/32/412_2.png) [@Fay\_king](https://community.pix4d.com/u/Fay_king)\
**Post date:** [August 18, 2016, 5:22pm UTC](https://community.pix4d.com/t/gcps-floating-in-the-air/5494/2 "2016-08-18T17:22:18Z")

</div>

Rogelio,

This is normal. &nbsp;

We mark a few GCP’s in the Basic Editor, then mark All GCP’s in the Raycloud. &nbsp;Be sure to “APPLY” your edits.

Start here:

[https://support.pix4d.com/hc/en-us/articles/202558699-Using-GCPs#gsc.tab=0](https://support.pix4d.com/hc/en-us/articles/202558699-Using-GCPs#gsc.tab=0)&nbsp;

---

<div class="post-metadata">

**Author:** ![rogelio\_flroes](https://avatars.discourse-cdn.com/v4/letter/r/d78d45/32.png) [@rogelio\_flroes](https://community.pix4d.com/u/rogelio_flroes)\
**Post date:** [August 18, 2016, 5:38pm UTC](https://community.pix4d.com/t/gcps-floating-in-the-air/5494/3 "2016-08-18T17:38:34Z")

</div>

Ryan,

&nbsp;

I did some research after I posted my problem and you are correct. I added marks for every GCP and reoptimize the project. I still need to get better at refining the GCP locations for each image but I got to this point at least. Thank you

---

<div class="post-metadata">

**Author:** ![Fay\_king](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/fay_king/32/412_2.png) [@Fay\_king](https://community.pix4d.com/u/Fay_king)\
**Post date:** [August 19, 2016, 12:00pm UTC](https://community.pix4d.com/t/gcps-floating-in-the-air/5494/4 "2016-08-19T12:00:36Z")

</div>

Rogelio,

Use Pix4DTagger w/ it’s targets and you will never have to find/pick/refine a GCP again.

GCP’s are marked automatically and it works great.&nbsp;

&nbsp;