D415 vs D435 pattern projector

[_xct]

Why does D435 feature inferior-quality pattern projector? If you take a picture from D435 using the pattern from D415, the point cloud will be less noisy and better overall. Also because points in D435 are more sparse, you often have jagged edges on different surfaces (like boxes), because there are not enough points at the edge.

[MartyG]

The D435 has a wider field of view than the D415 and a wide IR imager component, compared to the 'standard' sized one in the D415. It also has a faster 'global' shutter for its IR instead of a slower 'rolling' shutter on the D415. This makes the D435 better able to sense fast motion. A consequence of this hardware difference though is that the D415 model has approximately 2.5x the image quality of the D435.

[_xct]

Is it not possible to make a wide IR imager with dense pattern?

[MartyG]

I believe that the wide IR imager lets more light into it, which helps to account for the difference in quality. The 400 Series cameras are paired with a dedicated 'Vision Processor D4' component that processes captured data and gives some ability to make adjustments to the image data with software algorithms.

You can also change the properties of the light entering the sensor yourself. You can use your own choice of 'cover material' (the transparent material on the front of the camera that covers the imagers) if using the caseless 'Depth Module Kit' versions of the camera, or apply a micro-thin filter film in front of the imager.

The camera's configuration can be changed in software with Visual Presets that alter the balance of the camera's properties for greater accuracy, fill density, or a balanced 'Default' mode.

https://github.com/IntelRealSense/librealsense/wiki/D400-Series-Visual-Presets#preset-table

You can select a Preset from the top of the options side-panel in the RealSense Viewer or load them into your own script. You can also create your own custom preset in a 'json' file. This can be defined easily by defining settings in the RealSense Viewer and then exporting them as a json from the Viewer using an icon on the toolbar at the top of the side-panel.

If you would like to file an official Feature Request for a different imager then you can do so at the RealSense GitHub by visiting the link below and clicking the New Issue button.

https://github.com/IntelRealSense/librealsense/issues

[_xct]

I think we went offtrack here. My question was about the pattern projector (not the cameras), because the one from D415 provides better, denser texture.

[MartyG]

I apologize for the misunderstanding. There is indeed a difference between the IR Projector's dot pattern of the D415 and D435.

An external LED Projector can be used with the camera that enables a superior image quality because it greatly reduces the 'laser speckle' noise effect on the image that the laser-based projector of the 400 Series can produce. Pages 6 and 7 of Intel's camera tuning best practices guide give guidelines about using an external projector.

https://www.intel.com/content/dam/support/us/en/documents/emerging-technologies/intel-realsense-technology/BKMs_Tuning_RealSense_D4xx_Cam.pdf