# Follow-up: Why is the orthophoto radial or curved? (M3T, PV plant) – gps-accuracy fixes it

**URL:** <https://community.opendronemap.org/t/follow-up-why-is-the-orthophoto-radial-or-curved-m3t-pv-plant-gps-accuracy-fixes-it/26993>\
**Category:** ODM\
**Created:** [October 11, 2026, 7:48pm UTC](https://community.opendronemap.org/t/follow-up-why-is-the-orthophoto-radial-or-curved-m3t-pv-plant-gps-accuracy-fixes-it/26993 "2026-10-11T19:48:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Maurice.Sobiera](https://community.opendronemap.org/user_avatar/community.opendronemap.org/maurice.sobiera/32/6956_2.png) [@Maurice.Sobiera](https://community.opendronemap.org/u/Maurice.Sobiera)\
**Post date:** [October 11, 2026, 7:48pm UTC](https://community.opendronemap.org/t/follow-up-why-is-the-orthophoto-radial-or-curved-m3t-pv-plant-gps-accuracy-fixes-it/26993/1 "2026-10-11T19:48:57Z")

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@BofanLi follow-up to [Why is the orthophoto generated using ODM radial or somewhat curved?](https://community.opendronemap.org/t/21046) (closed now).

We processed your 64 images (odm\_task8\_partial\_images). With default settings the PV rows come out clearly bent – same as your screenshot.

**Cause:** it is essentially one long strip over very uniform panels (only ~28 000 reconstructed points). The self-calibrated lens distortion plus the default GPS weight (`gps-accuracy`, 3 m by default) let the bundle adjustment bend the strip (“banana” effect).

What we tried:

- `use-fixed-camera-params: true` → much worse (model breaks up).
- **`gps-accuracy: 1`** → the rows are almost straight; GPS residual 0.94 m instead of 1.52 m.

 ![Orthophoto with default settings (top) and gps-accuracy 1 (bottom)](https://community.opendronemap.org/uploads/default/original/3X/5/e/5e8e0bd6a73ff9f58e2f068fef1ec0d1b27bfa68.jpeg)  
_Orthophoto with default settings (top) and gps-accuracy 1 (bottom)_

So for this kind of strip flight: lower `gps-accuracy` (1 m, or the real accuracy of your positions), and if possible fly a second, parallel line or a cross line – that removes the bending completely.