Rendering Ambient Occlusion only

Unity Engine
, ,
1

Hi!

For research purposes, I would like to only output the results from the ambient occlusion stage to the final render target. I would like this to work both for SSAO and RTAO. What would be the easiest way to achieve this? Would really appreciate suggestions!

Regards!

2

Hello,

To extract the Ambient Occlusion only you can use our AOV API: Arbitrary Output Variables | High Definition RP | 10.0.0-preview.27
It should work with both AO types.

3

Thanks! I will try it!

4

Hi, sorry I need to clarify. The AOV API only export Ambient Occlusion from the Material (i.e the user input), it don’t export RTAO or SSAO.

We have a debug mode which allow to output Ambient Occlusion only. Windows → Render Pipeline Debug → Lighting → FullScreenDebug mode → Ambient Occlussion

5

Thanks for the clarification! I was actually going to ask about this because I noticed the difference. Is there any way to record the FullScreenDebug rendering information, the same way that I can record using AOV Recorder?

I did try to write a script to do this, but the output seems to be the AO from the Material and not the same as I can see when using FullScreenDebug mode. The script is based on the example from the Unity Manual on AOVs.

public class AOVOut : MonoBehaviour
{
    RTHandle tempRt;
    Texture2D readBackTex;

    int frame_count = 0;


    // Start is called before the first frame update
    void Start()
    {

        var camera = gameObject.GetComponent <Camera>();
        if (camera != null )
        {
            var additionalCameraData = gameObject.GetComponent<HDAdditionalCameraData>();
            if(additionalCameraData != null)
            {
                var aovRequest = AOVRequest.NewDefault();
                AOVBuffers[] aovBuffers = null;
                CustomPassAOVBuffers[] customPassAovBuffers = null;

                aovRequest.SetFullscreenOutput(DebugFullScreen.ScreenSpaceAmbientOcclusion); // Even though I request DebugFullScreen.ScreenSpaceAmbientOcclusion, the output is not the same that I can see in the Render Pipeline Debug tool

                aovBuffers = new[] { AOVBuffers.Output };

                tempRt = RTHandles.Alloc(camera.pixelWidth, camera.pixelHeight);

                var aovRequestBuilder = new AOVRequestBuilder();
                aovRequestBuilder.Add(aovRequest,
                    bufferId => tempRt,
                    null,
                    aovBuffers,
                    customPassAovBuffers,
                    bufferId => tempRt,
                    (cmd, textures, customPassTextures, properties) =>
                    {
                        if (textures.Count > 0)
                        {
                            readBackTex = readBackTex ?? new Texture2D(camera.pixelWidth, camera.pixelHeight, TextureFormat.RGBAFloat, false);
                            RenderTexture.active = textures[0].rt;
                            readBackTex.ReadPixels(new Rect(0, 0, camera.pixelWidth, camera.pixelHeight), 0, 0, false);
                            readBackTex.Apply();
                            RenderTexture.active = null;
                            byte[] bytes = readBackTex.EncodeToPNG();
                            System.IO.File.WriteAllBytes($"output_{frame_count++}.png", bytes);
                        }
                    });

                var aovRequestDataCollection = aovRequestBuilder.Build();
                additionalCameraData.SetAOVRequests(aovRequestDataCollection);

            }
        }

    }

}
6

Hi, there is no way currently with AOV API, this is something we will add in the future (around 22.1 release).