How to get distance in python

[Karin-Sugi]

Hi, i'm trying to get distance with realsense D435i in python. However, i could find little python example codes which get distance data, not image.

Now, I got an error saying

get_distance(): incompatible function arguments. The following argument types are supported:
    1. (self: pyrealsense2.pyrealsense2.depth_frame, x: int, y: int) -> float
   
Invoked with: <pyrealsense2.frame Z16 #1>, 424.0, 240.0

I think this supported argument type is not what i mean...

I know it's too basic question, but can any one tell me how to get distance of the point (x,y) or get distance of all the frame in python??

I put my code below as well.

import pyrealsense2 as rs
import numpy as np

pipeline = rs.pipeline()

# Start streaming
pipeline.start()

frames = pipeline.wait_for_frames()
depth = frames.get_depth_frame()

width = depth.get_width()
height = depth.get_height()

dist = depth.get_distance(width/2, height/2)
print(dist)

# Stop streaming
pipeline.stop()

[MartyG-RealSense]

Hi @Karin-Sugi Your code looks fine to me, so I am not sure why it is erroring. Does the error still occur if you specifically define width and height as being int values?

dist = depth.get_distance(int(width/2), int(height/2))

[Karin-Sugi]

Hi @MartyG-RealSense Your code did work!! I could get the data. Thanks.

On the other hand, in my search, some people use depth_scale * depth_frame to get distance data. What is the difference between them?

[MartyG-RealSense]

The camera produces raw pixel depth values in a format called uint16_t. Multiplying the uint16_t value by the depth unit scale of the camera provides a distance value in meters.

For example, the default depth scale of the 400 Series cameras is 0.001 (meters). If the raw uint16_t pixel depth value was 4500 then multiplying it by a depth unit scale of 0.001 would give 4500 x 0.001 = 4.5 (meters distance).

depth.get_distance though is an alternative way to obtain the distance in meters without having to use the above 'uint16_t x depth scale' formula. There is a discussion at #7264 where the two methods are compared.

[MartyG-RealSense]

Hi @Karin-Sugi Do you require further assistance with this case, please? Thanks!

[Karin-Sugi]

Thanks for your assistance!!

[MartyG-RealSense]

You are very welcome, @Karin-Sugi - thanks for the update!