# Debugging NRD
Currently NRD plugin supports debbugging through the validation layer.

# VALIDATION LAYER

![Validation](media/Validation.png)

If `NRDCommonSettings::enableValidation = true` *REBLUR* & *RELAX* denoisers render debug information into `OUT_VALIDATION` output. Alpha channel contains layer transparency to allow easy mix with the final image on the application side. Currently the following viewport layout is used on the screen:

| 0 | 1 | 2 | 3 |
|---|---|---|---|
| 4 | 5 | 6 | 7 |
| 8 | 9 | 10| 11|
| 12| 13| 14| 15|

where:

- Viewport 0 - world-space normals
- Viewport 1 - linear roughness
- Viewport 2 - linear viewZ
  - green = `+`
  - blue = `-`
  - red = `out of denoising range`
- Viewport 3 - difference between MVs, coming from `IN_MV`, and expected MVs, assuming that the scene is static
  - blue = `out of screen`
  - pixels with moving objects have non-0 values
- Viewport 4 - world-space grid & camera jitter:
  - 1 cube = `1 unit`
  - the square in the bottom-right corner represents a pixel with accumulated samples
  - the red boundary of the square marks jittering outside of the pixel area

*REBLUR* specific:
- Viewport 7 - amount of virtual history
- Viewport 8 - number of accumulated frames for diffuse signal (red = `history reset`)
- Viewport 11 - number of accumulated frames for specular signal (red = `history reset`)
- Viewport 12 - input normalized `hitT` for diffuse signal (ambient occlusion, AO)
- Viewport 15 - input normalized `hitT` for specular signal (specular occlusion, SO)