# Ray cloud hovering above cameras and GCPs Z location error. **URL:** \ **Category:** PIX4D International\ **Created:** [July 28, 2025, 5:37am UTC](https://community.pix4d.com/t/ray-cloud-hovering-above-cameras-and-gcps-z-location-error/33885 "2025-07-28T05:37:55Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![pix4d25nesac](https://avatars.discourse-cdn.com/v4/letter/p/ea5d25/32.png) [@pix4d25nesac](https://community.pix4d.com/u/pix4d25nesac)\ **Post date:** [July 28, 2025, 5:37am UTC](https://community.pix4d.com/t/ray-cloud-hovering-above-cameras-and-gcps-z-location-error/33885/1 "2025-07-28T05:37:55Z")
We’ve encountered an issue in PIX4D when processing datasets captured using the double grid survey method. In this case, the ray cloud appears to be floating significantly above the camera positions. Additionally, the Z-coordinates of the GCPs are located well below the ray cloud. In contrast, when processing data from a single grid survey of the same area, the ray cloud aligns much more accurately, with the GCPs only slightly above the ray cloud, as expected. The screenshots of the problems are shown below. ![Error_pix4dmapper](https://global.discourse-cdn.com/pix4d/original/2X/3/3676b1c17d4ab6bb8d5766cb7825de2097c4520f.jpeg) ---
**Author:** ![Kapil\_Khanal](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/kapil_khanal/32/304_2.png) [@Kapil\_Khanal](https://community.pix4d.com/u/Kapil_Khanal)\ **Post date:** [July 28, 2025, 10:03pm UTC](https://community.pix4d.com/t/ray-cloud-hovering-above-cameras-and-gcps-z-location-error/33885/3 "2025-07-28T22:03:38Z")
Hello @pix4d25nesac, can you upload the quality report. Normally, if the GCPs are below or above the raycloud, it is mainly due to the inaccuracy of the image geolocation. This shouldn’t affect the accuracy of your map because you are using GCPs and the project aligns based on GCPs. If you have difficulty marking GCPs, you can use basic editor. > **[How to add / import GCPs using the Basic GCP/MTP Editor - PIX4Dmapper](https://support.pix4d.com/hc/en-us/articles/202560099)** > > This article explains how to add and import ground control points (GCPs) when using the Basic GCP/MTP Editor. 1. On the Menu bar, click Project \> GCP / MTP Manager... 2. In the GCP/MTP Manager sectio From the issue related to the point cloud being above the image location, it is not expected so would like to see the quality report. The first screenshot shows the images are not processed correctly. ---
**Author:** ![pix4d25nesac](https://avatars.discourse-cdn.com/v4/letter/p/ea5d25/32.png) [@pix4d25nesac](https://community.pix4d.com/u/pix4d25nesac)\ **Post date:** [July 29, 2025, 4:11am UTC](https://community.pix4d.com/t/ray-cloud-hovering-above-cameras-and-gcps-z-location-error/33885/4 "2025-07-29T04:11:18Z")
[Nalanda\_with ibase\_report.pdf](https://community.pix4d.com/uploads/short-url/tjUf9PfwJl1KS54mO1UsNshn99p.pdf) (2.7 MB) This is the quality report. The main issue arises when I attempt to perform corrections—no images are displayed upon clicking each GCP. ---
**Author:** ![Kapil\_Khanal](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/kapil_khanal/32/304_2.png) [@Kapil\_Khanal](https://community.pix4d.com/u/Kapil_Khanal)\ **Post date:** [July 29, 2025, 3:46pm UTC](https://community.pix4d.com/t/ray-cloud-hovering-above-cameras-and-gcps-z-location-error/33885/5 "2025-07-29T15:46:15Z")
Hello, The issue is with the image geotags, they are not seeing the images and raycloud in the correct altitude. In this case, you can use the Basic Editor to mark the GCPs in place of raycloud. To mark the GCPs, using Basic Editor, you can select 3-4 GCPs and mark around 4-5 images and then reoptimize your project. This should bring the project on a correct height based on the GCPs and then you can use raycloud to mark remaining GCPs. > **[How to add / import GCPs using the Basic GCP/MTP Editor - PIX4Dmapper](https://support.pix4d.com/hc/en-us/articles/202560099)** > > This article explains how to add and import ground control points (GCPs) when using the Basic GCP/MTP Editor. 1. On the Menu bar, click Project \> GCP / MTP Manager... 2. In the GCP/MTP Manager sectio I would also recommend using Alternative and All Prior for the Camera Calibration Process.