Depth maps captured by the ZED store a distance value (Z) for each pixel (X, Y) in the image. The distance is expressed in metric units (meters for example) and calculated from the back of the left eye of the camera to the scene object.
Depth maps cannot be displayed directly as they are encoded on 32 bits. To display the depth map, a monochrome (grayscale) 8-bit representation is necessary with values between [0, 255], where 255 represents the closest possible depth value and 0 the most distant possible depth value.
You can find all the information you need here on the documentation that we have published:-https://www.stereolabs.com/docs/depth-sensing/.
Additional Resources: