depth mode D455(4:3) restricted area for components arround camera
Question 1.
I plan to use depth mode of the RealSenseD455. depth 640 x 480 (4:3)
It will be integrated into a device, but is there a specification on the restricted area, i.e. what area around the camera the components must not be placed in?
Question 2
It is my understanding that the description H:75 degrees represents the angle of view of the IR cameras on both sides.
It is stated in data sheet that only the area where the angle of view of the IR cameras on both sides overlap can be used to measure depth.
If a component is placed within the angle of view of only one camera without overlap, will this have an adverse effect on the depth measurement?
Hisatsugu HORIUCHI [FUJIFILM Corporation]
[R & D Headquarters Medical System Development Center MS XR]
+81-90-8778-0944
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Hi Hisatsugu Horiuchi Thanks very much for your questions.
1. The D455 camera model has a minimum depth sensing distance of around 0.5 meters / 50 cm. When objects are nearer to the camera than this, their depth detail will progressively break up the closer that the object gets to the camera until the object disappears from the image.
It is possible to reduce the minimum depth sensing distance to render objects that are closer to the camera than 0.5 meters if you use a setting called Disparity Shift. Increasing the value of Disparity Shift reduces the camera's minimum depth distance, though it also reduces the maximum distance that the camera can depth-sense to.
If you need to depth sense objects at closer range and have the ability to choose a different camera model then the D435 model (or the D435i if you need the IMU gyro / accelerometer component) may suit your needs, as objects can be placed around 0.15 meters / 15 cm from the camera. Whilst D435 type cameras have a smaller field of view size than D455, this may not matter if you plan to use 640x480 resolution which has a limited size view of the scene anyway.
If your project is medical and you need high accuracy, high quality depth sensing at very close range then the D405 model is particularly suited for body area scanning applications. It has an ideal depth sensing range of 7 cm to 50 cm, though it can render depth up to a couple of meters from the camera.
2. If an object is placed to the left or right of the center of the camera's field of view then some of the detail of the outer edge of the object may be excluded from the depth image (which is constructed from images captured by both the left and right sensors even if the object is outside of one sensor's view).
The smaller the resolution that is used, the more detail at the sides of the image that will be cut off. Depth measurements that are taken at the outer edges of the viewpoint may also be less accurate than those at the center of the camera's view.
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We appreciate for your prompt response.
3.
In the data sheet, we see H:75.
Does this mean that the left and right IR cameras have a 75° angle of view?4.
The depth area will be cut at the outer edge of the FOV.
Then, is there any negative effect on the depth measurement if something is placed in that area? -
3. Yes, the left and right IR sensors on the D455 camera model have an FOV size that is 75 degrees wide in the horizontal, as shown on your diagram.
4. If an object was half in and half out of the edge of the FOV then the half that is outside of the edge of the FOV likely would not be captured on the depth image. The half of the object that is just inside the edge of the FOV may have broken-up depth detail (holes / gaps) or inaccurate depth values. It would only negatively affect that area of the depth image though, not the entire image.
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