Configure an Align Color Depth Homography View

When you have a depth image and you need it to overlay on top of a color image exactly, a homography matrix can apply the necessary distortions to the depth image for it to overlap.

Navigate to the Config tab of your robot’s page in the Viam app. Click on the Components subtab and click Create component. Select the camera type, then select the align_color_depth_homography model. Enter a name for your camera and click Create.

Configuration of an align color depth homography view in the Viam app config builder.

Edit and fill in the attributes as applicable.

{
    "name": "<your-camera-name>",
    "type": "camera",
    "model" : "align_color_depth_homography",
    "attributes": {
        "intrinsic_parameters": {
            "width_px": <int>,
            "height_px": <int>,
            "fx": <float>,
            "fy": <float>,
            "ppx": <float>,
            "ppy": <float>
        },
        "homography": {
            "transform": [ <float>, <float>, <float>,
                           <float>, <float>, <float>,
                           <float>, <float>, <float> ],
            "depth_to_color": <boolean>,
            "rotate_depth_degs": <int>
        },
        "color_camera_name": "<your-camera-name>",
        "depth_camera_name": "<your-camera-name>",
        "output_image_type": "<color|depth>",
        "distortion_parameters": {
            "rk1": <float>,
            "rk2": <float>,
            "rk3": <float>,
            "tp1": <float>,
            "tp2": <float>
        },
        "debug": <boolean>
    }
}

The following attributes are available for align_color_depth_homography views:

NameTypeInclusionDescription
intrinsic_parametersobjectRequiredThe intrinsic parameters of the camera used to do 2D <-> 3D projections:
  • width_px: The expected width of the aligned image in pixels.
  • height_px: The expected height of the aligned image in pixels.
  • fx: The image center x point.
  • fy: The image center y point.
  • ppx: The image focal x.
  • ppy: The image focal y.
homographyobjectRequiredParameters that morph the depth points to overlay the color points and align the images:
  • transform: 9 floats representing the 3x3 homography matrix of the depth to color, or color to depth camera.
  • depth_to_color: Whether to transform depth camera points to color camera points.
  • rotate_depth_degs: Degrees by which to rotate the depth camera image.
color_camera_namestringRequiredname of the color camera to pull images from.
depth_camera_namestringRequiredname of the depth camera to pull images from.
output_image_typestringRequiredSpecify color or depth for the output stream.
distortion_parametersobjectOptionalModified Brown-Conrady parameters used to correct for distortions caused by the shape of the camera lens:
  • rk1: The radial distortion x.
  • rk2: The radial distortion y.
  • rk3: The radial distortion z.
  • tp1: The tangential distortion x.
  • tp2: The tangential distortion y.
debugbooleanOptionalEnables the debug outputs from the camera if true.
Default: false

View the camera stream

Once your camera is configured and connected, go to the Control tab, and click on the camera’s dropdown menu. Then toggle the camera or the Point Cloud Data view to ON. If everything is configured correctly, you will see the live video feed from your camera. You can change the refresh frequency as needed to change bandwidth.

Example Camera view inside Viam app

Next Steps

Calibrate a Camera

Calibrate a camera and extract the intrinsic and distortion parameters.

transform

Instructions for transforming a camera.

Vision
Vision

The vision service enables your smart machine to use its on-board cameras to intelligently see and interpret the world around it.



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