Two D435i IR related problem
Two D435i installation method is shown in the following figure：
I turned on the infrared dot matrix camera (IR) of the d435i above and turned off the infrared dot matrix camera (IR) of the d435i below. Due to the influence of the structural light emitted by the d435i above, the pictures generated in the d435i binocular camera below will have speckle / spot. I hope to obtain the pictures without speckle / spot from the d435i binocular camera below. How can I do this?
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Hello, you can disable the projector component and its infrared dot pattern in the RealSense Viewer by selecting Off from the drop-down menu beside the Emitter Enabled option.
You can also reduce the visibility of the dot pattern without completely turning off the projector by reducing the value of the Laser Power option.
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Thank you very much for your reply! My question is that when two d435i are placed as shown in the above picture, the lower d435i has turned off the emitter enabled option, and the upper one has turned on the emitter enabled option. How can I get an image without spots from the lower d435i binocular camera?
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If the upper camera is projecting an IR dot pattern then a camera mounted below it that is observing the same scene will see those dots too even if its own projector is disabled. This is because the upper camera's projector is casting the dots onto physical objects and surfaces in the scene, so the ability to see the dots is not limited only to the camera that is projecting them.
As mentioned above, you can disable the projector and this will make the dot pattern disappear from the view of all cameras in the scene.
If you need the illumination that the projector provides but do not want the dot pattern, you could disable the projector and provide additional external illumination in the scene. This could be an ordinary strong light-source or a patternless IR illuminator lamp.
400 Series cameras use the IR dots as a 'texture source' to analyze the surfaces that the dots are cast onto for depth information, but in the absence of a dot pattern the camera can alternatively make use of any ambient light source whose frequency it can see to analyze surfaces for depth information.
If your application is measuring depth at close range (7 cm to 50 cm) then you could consider using a RealSense D405 camera model as the lower camera, as it is fitted with an IR-Cut filter on its sensors that make the dots invisible to the camera whilst still being visible to other RealSense camera models.
If changing camera model is not practical for your project then you could retro-fit an IR-Cut filter (also known as a shortpass filter) to the outside of the lower camera, as described in Section 4.3 of Intel's white-paper document about using optical filters with 400 Series cameras.
https://dev.intelrealsense.com/docs/optical-filters-for-intel-realsense-depth-cameras-d400
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Hello, sorry to disturb you again. I want to confirm with you again whether the d435f/d405 can be installed in the above way, whether the binocular camera cannot receive the speckle emitted by d435i, and the binocular image of d435f/d405 has no light spot, thank you! If so, I'm going to buy one of them!
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The filters on the D405 and D435f camera models have different purposes. The D405's filter is IR Cut which blocks infrared light frequencies and so makes the IR dot pattern invisible to it. So a pattern that is projected by another camera onto the scene will still be there but will not be visible to the D405.
The IR Pass filter on the D435f allows near-infrared frequencies and absorbs visible light frequencies.
So if you need to exclude infrared frequencies from being visible to the camera then the D405 would be the appropriate choice between those two camera models.
The D435i that you already have and the D405 both have M3 size rear mounting holes. The pair of holes on the D405 are closer together than the D435i and the D405 casing is higher so it may not fit on your current tripod mount due to the mounting position of the D435i that would be above it. It is also worth bearing in mind that the D405 will have different characteristics to the D435i, including a different field of view (FOV) size.
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The D435f will not cut out the multiple white dots of the infrared pattern if that is what you mean. The D405 does, shown in the same scene observed with a D405. Like your own scene, I placed a D435i above the D405, projecting a dot pattern. The D435i shows the dot pattern and the D405 does not.
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The D405 is designed for close-range, high accuracy sensing with an ideal depth measuring range of 7cm to 50 cm so it would not be a suitable choice if you are going to be depth-sensing objects or surfaces at distances further than 50 cm / 0.5 m. The distance limitation does not apply to the infrared view though.
T265 is equipped with an IR-Cut filter on its fisheye sensors like the ones on the D405's sensors and so also cannot see infrared frequencies such as the dot pattern. This is because it can be paired with a 400 Series camera on the same mount, and its IR-Cut filter means that it cannot experience interference from the dot pattern of a 400 Series camera. The quote below is from the data sheet document for the T265.
The T265 is an End of Life (retired) RealSense model though, so you may not be able to obtain a replacement if you need to purchase another one in the future.
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Sorry to disturb you again! My boss needs me to confirm two things:
1. Is it convenient for you to send a comparison picture as shown in the above figure (d435i and d405). With t265 and d435i, my boss wants to see the effect picture of t265 when d435i emits light spot.
2. If you want to refit the d435i so that there is no spot on the binocular image like the d405, is it OK to add an IR cut fliter outside the binocular camera of the d435i respectively? If so, can you send me a copy of the detailed parameters of IR cut fliter (I'm not sure if it's 750nm)?
Be deeply grateful! -
1. I do not have a T265 to test with at my location as others handle T265 related cases. I can point you towards some useful references for using a T265 and 400 Series camera together though.
T265 and Depth Cameras 400 Series - Better Together
https://www.intelrealsense.com/depth-and-tracking-combined-get-started/
Another example of a T265 + D435 paper published by Intel is here:
T265 and D435 - Tracking and Depth
https://dev.intelrealsense.com/docs/depth-and-tracking-cameras-alignment
YouTube - Visual Navigation for Wheeled Autonomous Robots (44 minutes)
The section where T265 and D435 are introduced together begins at 17 minutes 30 seconds into the video.
https://www.youtube.com/watch?v=62vm0_RZ1nU
In regard to an image of D435i and T265 observing the same scene, the animated image in the section linked to below should be a useful illustration.
https://dev.intelrealsense.com/docs/rs-multicam#expected-output
Also, an image taken from the rs-capture example program where a T265 and D435i are attached to the same computer.
2. Yes, you can attach an optical filter to the outside of the camera's casing. This could be done by 3D printing a custom holder clip to put around the camera casing like the example here for D435:
https://www.thingiverse.com/thing:5140445
Alternatively, one RealSense user simply wrapped rubber bands around the camera to hold the filter in place.
If you are adding filters to the infrared sensors then they must be applied over both the left and right sensors.
You can also find 3D printing models for T265 / D435 mounts amongst the RealSense blueprints on Thingiverse.
https://www.thingiverse.com/tag:realsense
There are not detailed parameters available for the built-in IR-Cut filters on RealSense cameras. Intel's white-paper document about optical filters provides the following graph though describing the wavelength characteristics of a Shortpass (IR-Cut) filter.
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You can read detailed intrinsic and extrinsic calibration information from your camera by running the rs-enumerate-devices tool with the launch command below:
rs-enumerate-devices -c
If you are using Windows, instructions for doing so in the Windows Command Prompt interface can be found in the link below.
https://github.com/IntelRealSense/librealsense/issues/3569#issuecomment-615365409
If you are seeking the Rotation and Translation calibration extrinsics between left infrared and depth, you can scroll down the list of calibration data outputted by the tool until you find the section titled Extrinsic from "Infrared 1" to "Depth"
Infrared 1 (the left infrared sensor) and depth originate from the same sensor.
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Hi,MartyG,long time no see, sorry to bother you again, I encountered a problem when calling D435i official API to get Pose data. In the statement in the figure below, when it runs to get_pose_data, the program will be interrupted. What is the problem?
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Hi, MartyG, sorry to bother you again. I'm having some issues with the D435i depth map accuracy.
My project requirement is to do gesture recognition, so I need to get accurate gesture depth map. As shown in the picture below, when I turn on IR, many points of my hand are missing in the depth map, showing black pixels, which greatly affects the accuracy of my gesture recognition. Is this a problem with the parameter settings of the D435i camera or is this the depth recognition accuracy of the D435i?
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It's no bother at all. :)
The D435i has a default minimum depth sensing distance of 0.1 meters / 10 cm, so if the hand / arm is nearer to the camera than 10 cm then the depth image will start to progressively break up as the hand / arm moves closer to the camera.
You can reduce the minimum distance of the camera to allow an object / surface to be positioned closer to the camera by increasing a setting called Disparity Shift that can be found under the Stereo Module > Advanced Controls > Depth Table section of the Viewer's options side-panel. I recommend changing this setting from the default '0' to '50' or '100'.
Increasing disparity shift reduces the minimum distance but also reduces the maximum observable depth distance of the camera. This should not be a problem if you are performing close-range sensing though.
Another method of improving the depth image at close range is to change the Depth Units from the default '0.001' to a smaller '0.0001' value. The Depth Units option can be found under Stereo Module > Controls. You can type the 0.0001 value in with the keyboard by left-clicking on the pencil icon beside the option.
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After extensive testing with all Viewer options, I found that the best approaches were either to move the hand / arm a little further away from the camera or to switch to the D405 camera model, which is designed for high accuracy, high quality images at very close range (ideal depth range 7 - 50 cm). An image from a D405 at around 10 cm from the camera is shown below.
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