# facade images have incorrect elevation

**URL:** <https://community.pix4d.com/t/facade-images-have-incorrect-elevation/27105>\
**Category:** PIX4Dmapper\
**Created:** [July 13, 2023, 11:32am UTC](https://community.pix4d.com/t/facade-images-have-incorrect-elevation/27105 "2023-07-13T11:32:13Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![tom1](https://avatars.discourse-cdn.com/v4/letter/t/b487fb/32.png) [@tom1](https://community.pix4d.com/u/tom1)\
**Post date:** [July 13, 2023, 11:32am UTC](https://community.pix4d.com/t/facade-images-have-incorrect-elevation/27105/1 "2023-07-13T11:32:13Z")

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I’m creating a model of a building and after flying a crosshatch nadir mission I then flew manually around the building at a low altitude capturing the facade to enhance the model. I flew with the same drone on the same day as the mapping mission. I processed the two datasets separately and when merged the bottom or the “ground” level of the facade images line up with the roofs surface. Any incite would be appreciated. Thanks

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<div class="post-metadata">

**Author:** ![tom1](https://avatars.discourse-cdn.com/v4/letter/t/b487fb/32.png) [@tom1](https://community.pix4d.com/u/tom1)\
**Post date:** [July 13, 2023, 11:43am UTC](https://community.pix4d.com/t/facade-images-have-incorrect-elevation/27105/2 "2023-07-13T11:43:36Z")

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Can I successfully realign by adding manual tie points after the first step and reprocess? Thanks

 ![IMG_5844](https://global.discourse-cdn.com/pix4d/original/2X/d/da2dbaea63e133dc0e2402c14c60d61b3e9524fd.jpeg)

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<div class="post-metadata">

**Author:** ![Daniele\_Lecci](https://sea2.discourse-cdn.com/pix4d/user_avatar/community.pix4d.com/daniele_lecci/32/9493_2.png) [@Daniele\_Lecci](https://community.pix4d.com/u/Daniele_Lecci)\
**Post date:** [July 19, 2023, 8:50am UTC](https://community.pix4d.com/t/facade-images-have-incorrect-elevation/27105/3 "2023-07-19T08:50:00Z")

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Hi @tom1,

Do you confirm you are following the procedure described here?

> **[How to merge projects - PIX4Dmapper](https://support.pix4d.com/hc/en-us/articles/202558529-How-to-merge-projects-PIX4Dmapper)**
>
> This article provides step-by-step instructions on how to merge projects in PIX4Dmapper. There are two parts when merging a project: Before merging projects and while merging projects.
> It is possib...

(You can also give it a try by adding all images to the same project.)

Are the two (sub-) projects comparable in terms of GSD?  
Are the quality reports of the subprojects “green” ✅ ?

A common cause for projects fail to align properly relative to each other is due to not enough matches between the subprojects:

- Add more common Ground Control Points or Manual Tie Points in the subprojects before merging.