Is there a way to remove points too far away when I save a .plt file?

[JimXu1989]

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Required Info
Camera Model	{ D400 }
Firmware Version	(Open RealSense Viewer --> Click info)
Operating System & Version	Linux (Ubuntu 20.04
Kernel Version (Linux Only)	(e.g. 4.14.13)
Platform	PC/Raspberry Pi/ NVIDIA Jetson / etc..
SDK Version	{ legacy / 2.<45>.<0> }
Language	python

Issue Description

I use the following code to save a .ply file, while, there are so many far away points which I do not need
pc.map_to(color_frame)
points = pc.calculate(aligned_depth_frame)
points.export_to_ply('./ply_files/'+ str(filelen) + ".ply", color_frame)
As the pic shows:

Is there any way to clip the 3d points?

[MartyG-RealSense]

Hi @JimXu1989 You could use a threshold filter post-processing filter in Python to set a maximum depth distance so that the far-off points are excluded from the point cloud before it is imported to ply. An example of such a script is in the link below.

#8170 (comment)

Alternatively, you could import the ply file into the free MeshLab software tool and edit the data there.

https://www.meshlab.net/

[JimXu1989]

Hi @JimXu1989 You could use a threshold filter post-processing filter in Python to set a maximum depth distance so that the far-off points are excluded from the point cloud before it is imported to ply. An example of such a script is in the link below.

#8170 (comment)

Alternatively, you could import the ply file into the free MeshLab software tool and edit the data there.

https://www.meshlab.net/

Hi,
Thanks a lot for your reply!
When I fellow your reply,I met an error :
frames = pipeline.wait_for_frames()
// frames.get_depth_frame() is a 640x360 depth image
frames = threshold_filter.process(frames)
//Align the depth frame to color frame
aligned_frames = align.process(frames)

aligned_frames = align.process(frames)
TypeError: process(): incompatible function arguments. The following argument types are supported:
1. (self: pyrealsense2.pyrealsense2.align, frames: pyrealsense2.pyrealsense2.composite_frame) -> pyrealsense2.pyrealsense2.composite_frame

Invoked with: <pyrealsense2.pyrealsense2.align object at 0x7f8583f3c8b0>, <pyrealsense2.frameset Z16 BGR8 #7>

And the filtered frame don not have the attribute 'get_depth_frame'

Traceback (most recent call last):
File "/home/jim/realsense/librealsense/wrappers/python/examples/grab_rgbd.py", line 65, in
aligned_depth_frame = frames.get_depth_frame()
AttributeError: 'pyrealsense2.pyrealsense2.frame' object has no attribute 'get_depth_frame'

[MartyG-RealSense]

It is difficult to debug without seeing the whole script. Would it be possible to post your full script in the comments please?

For example, if the align code in your script is based upon align-depth2color.py, have you set up align_to in your script?

https://github.com/IntelRealSense/librealsense/blob/master/wrappers/python/examples/align-depth2color.py#L51-L52

[MartyG-RealSense]

Hi @JimXu1989 Do you require further assistance with this case, please? Thanks!

[MartyG-RealSense]

Case closed due to no further comments received.

[jianjuan]

Hi, I met the same question, I want to filter the background on the pointcloud, here are my codes:
``import pyrealsense2 as rs
print("Environment Ready!")

DEBUG = False
pipeline = rs.pipeline()
config = rs.config()
config.enable_stream(rs.stream.depth, 1280, 720, rs.format.z16, 30)
config.enable_stream(rs.stream.color, 1280, 720, rs.format.bgr8, 30)
pc = rs.pointcloud()
points = rs.points()
thresholder = rs.threshold_filter()
thresholder.set_option(rs.option.min_distance, 0.4)
thresholder.set_option(rs.option.max_distance, 0.9)

Start streaming

profile = pipeline.start(config)
align_to = rs.stream.color
align = rs.align(align_to)

Wait for a coherent pair of frames: depth and color

Skip the first 300 frames to set the auto exposure time

for x in range(100):
pipeline.wait_for_frames()

frames = pipeline.wait_for_frames()
frames = thresholder.process(frames)

Align the depth frame to color frame

aligned_frames = align.process(frames)

Get aligned frames

aligned_depth_frame = aligned_frames.get_depth_frame()
aligned_color_frame = aligned_frames.get_color_frame()
aligned_color_profile = rs.video_stream_profile(profile.get_stream(rs.stream.color))
color_intrinsics = aligned_color_profile.get_intrinsics()``

And I got this error:

It seems that threshold_filter has changed some properties of 'frames'? Can you help me with solving this?Thanks! @MartyG-RealSense

[MartyG-RealSense]

Hi @jianjuan You are performing alignment after post-processing (the threshold filter) which is Intel's recommendation, so that part looks fine.

In your frame skip routine, I believe that the line pipeline.wait_for_frames() could be deleted because the frames = pipeline.wait_for_frames() line will handle it correctly.

If you are only setting a maximum depth rendering distance and do not need to define a minimum distance too then the clipping distance method demonstrated in the SDK's align-depth2color Python alignment sample program may be able to perform this function instead of a threshold filter.

https://github.com/IntelRealSense/librealsense/blob/master/wrappers/python/examples/align-depth2color.py#L52

[jianjuan]

Thanks for your reply! However, my command is to clip distance from minimum distance to maximum distance, you see, in my applications, close objects are obstruct for my interested object. And I see that "realsense_viewer" can do threshold filter to obtain my ideal pointcloud, so is there a chance to do so in my code? Or, after thresholder.process(), is there any operation to convert data type of frame?

[MartyG-RealSense]

The threshold filter can be accessed in Python. #8170 (comment) has an example of a script for doing so that you can compare to your own code.

You will need to add a reference to min_distance to the script to define the desired minimum distance of the threshold filter, like in #3002 (comment)