11 votes
Accepted

what's the difference among rgb-d camera, depth camera, 3d camera, and stereo camera?

3D/Depth-Camera: The most inclusive terms, only means that the camera gives you 3d data. Stereo-Camera: One kind of 3D-Camera, consists (in most cases) of two gray-scale Cameras. RGBD-Camera: A ...
FooTheBar's user avatar
  • 1,375
9 votes

Camera selection for long range stereo vision system (up to 100 meters)

I still think this is off-topic, but it seems I need more space than a comment to show (answer?) why that is so. You are starting from some performance specifications and are looking to get to a set ...
Chuck's user avatar
  • 16k
4 votes

Why are two cameras mounted in paralle in stereo application?

Each camera needs to be defined by 6 variables (3 position, 3 orientation). This would mean that during the calibration process, a solver needs to find 12 variables. As this is done usually with an ...
Arun Lakshmanan's user avatar
4 votes
Accepted

Smart camera image processing on embedded GPU vs. in the cloud

Performance differences between using an embedded GPU vs. the cloud? For your context (to my mind, gesture recognition would ideally be realtime), the latency of going over the cloud would push me ...
OpenSorceress's user avatar
4 votes
Accepted

Visual Odometry terminology: Scale, Relative scale, absolute scale

What does the absolute scale mean? In this context, scale refers to what property related to an image? Essentially scale refers to the size of the object/scene that the camera sees. As a projective ...
edwinem's user avatar
  • 1,861
3 votes
Accepted

I am making a Ping pong-playing robot using two cameras to trace the ball (3D vision),what is the minimum Frame rate of the cameras?

The movement of the ping pong ball is going to be ballistic, so you really only need to know its 3d position in 3 different locations in order to fully constrain its motion. In reality, you will ...
Mark Omo's user avatar
  • 1,919
3 votes

Camera selection for long range stereo vision system (up to 100 meters)

I'll try to explain this in terms of software. Firstly, it is just next to impossible to have 100 metres (practically, 3 metres is like the best depth accuracy) and we need to be sure that the cameras ...
Prasad Raghavendra's user avatar
3 votes
Accepted

Difference between 3D Camera(using IR projection) and Stereo Camera?

"3D camera" is a generalisation that covers sensors that can observe a point-cloud or depth map of the scene they are observing. Some 3D cameras use a projector (via various ways) to improve the ...
Gouda's user avatar
  • 902
3 votes

Stereo Camera calibration with different camera types

It looks like what I saw when a colleague of mine was working with fisheye lenses; I found this post after doing an image search for "rectify fisheye image" and following the link from this picture. ...
Chuck's user avatar
  • 16k
3 votes
Accepted

How to produce a continuous variation of a discontinuous function?

It happens many times that set-points fed in our systems do change in a step-wise manner. Your intuition of filtering those variations is correct and represents a common practice. Here I'd give two ...
Ugo Pattacini's user avatar
3 votes
Accepted

Question about Lens distortion

You can only say that the distorted image coordinates are in the range (0-240, 0-180), since that's the image you are starting with. Typically you assume the dimensions of the undistorted image as ...
Peter Corke's user avatar
  • 1,702
3 votes
Accepted

Position vs Image based visual servoing?

The problem in both cases is to move the robot tool to some pose relative to an object. Let's assume the camera is attached to the end of a robot arm (eye in hand case) so we will consider this a ...
Peter Corke's user avatar
  • 1,702
3 votes

What is the relation between FOV, Focal Length and Sensor size in a Pin hole Camera Model?

The field of view can be shown to be $$ \theta = 2 \tan^{-1} \frac{D}{2f} $$ where $D$ is the dimension of the sensor (width or height) and $f$ is the focal length. You can derive this easily using ...
Peter Corke's user avatar
  • 1,702
3 votes
Accepted

How do I record video from webots simulated cameras?

Webots uses ffmpeg to create movies out of JPG images. The code snippet in Webots is located here. But since Webots embeds ffmpeg, you should be able to use it pretty easily from your controller ...
Olivier Michel's user avatar
3 votes

Detecting door blockage using computer vision

In your example image, you show what appears to be a fixed camera feed (for example, a security camera). If it is safe to assume that this is a fixed camera feed, this becomes much easier, since we ...
cst0's user avatar
  • 878
2 votes
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Syncing camera with other signals

Cameras that support syncing will probably do so via an external signal. Google "genlock" or "timecode sync" or "external trigger" to get started. For instance, here's a link to external trigger ...
hauptmech's user avatar
  • 4,435
2 votes

Analogue video to digital

You will need to have on-board processing if you plan to go with real time processing and the low latency premise. There is no other way around it, since transmitting the signal will introduce sizable ...
George ZP's user avatar
  • 550
2 votes

Perspective n Point - RPnP algorithm

Since you only have 4 points, you should use the P3P algorithm. 3 points give you up to 4 solutions, and you need a fourth point to decide which one is correct. So 4 is the minimum number of points ...
Dima's user avatar
  • 191
2 votes

Difference between 3D Camera(using IR projection) and Stereo Camera?

This isn't an answer so much as a series of questions to get you to consider an appropriate solution. I will, as usual :-), echo @BendingUnit22 and @Gouda - you appear to be fixated on a particular ...
Chuck's user avatar
  • 16k
2 votes

Image registration with ground plane for surround view

I don't know what the proper way to do this is but I can give you ideas to make it better: define an exact transformation for each camera. You could calibrate each camera using a grid pattern and by ...
Malcolm's user avatar
  • 571
2 votes
Accepted

My Plug Says It's USB, I can't Identify

USB is more than just a connector. It is a standard communications protocol, voltage levels, and even wiring colors. I suggest you get a standard USB cable, cut it in half, then splice in your ...
Ben's user avatar
  • 5,855
2 votes
Accepted

OpenCV get topdown view of planar pattern by using intrinsic and extrinsic from cameraCalibrate

Added OK, guys, simple mistake. I previously used warpPerspective to warp images instead of restoring. Since it works that way, I didn't read the doc thoroughly. It turns out that if it is for ...
ricecakebear's user avatar
2 votes

Depth cameras with varying illuminations

depth cameras are super cool. I have never worked with them before, but guess what? I have an opinion! lol. Have you considered using a lens to filter out the direct sunlight as a "cover" (kind of a ...
Mike's user avatar
  • 361
2 votes

Trigger two usb cameras at the same time

As you say, you can't trigger them at the exact same time without hardware capable of doing so. Some IMU's supply an external trigger pin, and I see no reason why you couldn't buy cameras that have a ...
sdfgeoff's user avatar
  • 151
2 votes
Accepted

How do I set all objects in my scene to be aligned with respect to the camera in Unity 3D?

I think the function you're looking for is TransformPoint(Vector3 position). You can describe something in coordinates that are local to the camera and use the <...
Chuck's user avatar
  • 16k
2 votes
Accepted

How to plot the 3D camera trajectory from a VSLAM output

That's simple. If you use matlab or opengl what you need to do is just drawing 3 axis at (tx,ty,tz). You need to convert quaternion to rotation matrix. (qx,qy,qz,qw) -> R(3x3 matrix) where each col ...
Chanoh Park's user avatar
  • 1,567
2 votes
Accepted

How to derive the camera trajectory from ICP

Yes that is correct. Easiest way is probably to work with the homogeneous 4x4 Tranform Matrix($T$) composed of $\begin{bmatrix}R & t\\0 & 1\end{bmatrix}$. Then your new pose is then just $T_i$ ...
edwinem's user avatar
  • 1,861
2 votes

How can I calibrate 3 cameras without knowing global pose of the object & camera locations? How can I find the pose of each camera wrt the first one?

The process you need to go through is actually similar to the camera calibration procedure in OpenCV or other software. The chessboard is replaced by your robot, and you can skip the intrinsic ...
edwinem's user avatar
  • 1,861
2 votes

Trouble aligning/calibrating camera with laser scanner

Within ros there is a lidar_camera_calibration package that should take care of this for you! Their github page has a detailed readme. If you aren't using ros, you can probably take a look at the core ...
Akhil Kurup's user avatar
2 votes
Accepted

ROS Publish Stereo Image From 2 USB Cameras

You can write a simple node which subscribes to the 2 RGB feeds, uses blob matching (look up Stereo matching in OpenCV or Stereo Binary SGBM) to create the stereo image, and publishes it. Alternately, ...
jaskaran singh sodhi's user avatar

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