# DFS undistort issue

Source: https://forum.modalai.com/topic/4315/dfs-undistort-issue
Category: VOXL SDK and Software (https://forum.modalai.com/category/47/voxl-sdk-and-software)
Tags: camera
Posted: 2025-04-04 00:48:15 UTC by SKA
Replies: 1 · Views: 868

## SKA · 2025-04-04 00:48:15 UTC

Hi! I'm trying to set up DFS using ar0144 cameras. I have the ```voxl-camera-server``` side working, and I'm able to view the stereo preview stream on ```voxl-portal```. I've set up my extrinsics and intrinsics using ```voxl-calibrate-cameras``` and have acceptable reprojection error. 
However, when I run ```voxl-dfs-server``` I get these errors:
```
ERROR computing undistort on left image in mcv_cvp_undistort_and_dfs_process
ERROR performing undistort+DFS pipeline
ERROR computing UD+DFS pipeline on CVP
```
Whether I enable or disable cvp rectification in the .conf file, I am facing errors. Let me know how I might be able to resolve this, thanks!

## Reply by Alex Kushleyev (ModalAI staff) · 2025-04-04 03:10:52 UTC

@SKA , this is most likely due to the max disparity value being too large - for 1280x800 resolution the maximum value is 32. 

the max disparity parameter limit is as follows:
- width <= 640 : max disparity = 64 (or less, in steps of 4)
- 640 < width <= 1280 : max disparity 32 (or less in steps of 4)
- 1280 < width <= 1920: 16, 12,8,  or 4

So in your case, you should update your max disparity parameter to 32 or less.

I have been testing AR0144 DFS recently and i also found that i needed to increase the min_threshold and cost_threshold from the default of 10 that was used for OV7251. I found that values in the range of 50-80 produced good results.

Here is some additional information regarding DFS:

**min_threshold:**
Lower bound for adjusting occlusion cost threshold.
When set to < cost_threshold, the occlusion penalty
is varied linearly from this minimum value from the first row
to the last row.
The last row takes cost_threshold.
Range: 0 to 100
Recommended range: 50 to 75
min_threshold <= cost_threshold

**cost_threshold:**
Occlusion cost threshold.
The higher the value, more smoothness is enforced.
Range: 0 to 100
Recommended range: 50 to 75

Alex