# Volume calculations and GCP placement

**URL:** <https://community.pix4d.com/t/volume-calculations-and-gcp-placement/5814>\
**Category:** PIX4Dmapper Questions/Troubleshooting\
**Created:** [December 14, 2016, 7:32pm UTC](https://community.pix4d.com/t/volume-calculations-and-gcp-placement/5814 "2016-12-14T19:32:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Ramiro\_Massa](https://avatars.discourse-cdn.com/v4/letter/r/c2a13f/32.png) [@Ramiro\_Massa](https://community.pix4d.com/u/Ramiro_Massa)\
**Post date:** [December 14, 2016, 7:32pm UTC](https://community.pix4d.com/t/volume-calculations-and-gcp-placement/5814/1 "2016-12-14T19:32:41Z")

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is it necessary to place GCP on top of a very large stockpile to get accurate volume calculations ?[https://www.youtube.com/watch?v=z-KcxsU7lWs](https://www.youtube.com/watch?v=z-KcxsU7lWs)&nbsp;

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**Author:** ![Marili\_Giovani](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/marili_giovani/32/187_2.png) [@Marili\_Giovani](https://community.pix4d.com/u/Marili_Giovani)\
**Post date:** [December 16, 2016, 2:41pm UTC](https://community.pix4d.com/t/volume-calculations-and-gcp-placement/5814/2 "2016-12-16T14:41:11Z")

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Hello Ramiro,

Ground Control Points (GCPs) will increase the absolute accuracy of the model, i.e. the model will be correctly placed on a coordinate system. However, by adding GCPs you will also improve the relative accuracy of the model.&nbsp;

You can check about accuracy here: &nbsp;[https://support.pix4d.com/hc/en-us/articles/202558889](https://support.pix4d.com/hc/en-us/articles/202558889)&nbsp;

Best Regards,&nbsp;