Questions tagged [3d]
The 3d tag has no usage guidance.
85
questions
12
votes
2answers
10k views
Analytical expression for the eigenvectors of a 3x3 real, symmetric matrix?
I am writing an algorithm that process 3D images based on the local moment of inertia.
I have a 3x3 real symmetric matrix, from which I need to find the eigenvalues. I have found a variety of ...
1
vote
1answer
23 views
Why not use synthetic datasets for training machine vision (deep learning) algorithms?
I am studying some examples of how to perform 3D instance segmentation in indoor scenes, and I have noticed many of the available datasets are from real environments. I was wondering with the ...
1
vote
1answer
36 views
Is there any way to do 3D (Voxel Data) feature detection?
In the 2D image processing, there are ways to find and match features of the image (like corner of the edges). However, I could not find the equivalent of that in the 3D-voxel data (Here voxel means a ...
0
votes
1answer
722 views
3D point cloud to 2.5D graycale image (metric) [Halcon?]
I have a problem ragarding transferring a point cloud to a 2.5D metric grayscale image (gray value gives depth information). I start with a three channel image of 32bit floats with each pixel ...
2
votes
2answers
48 views
Is there any simple algorithm to convert a sound source in 3d to volume and panning
I'm looking for a simple algorithm which calculates an approximation of volume and pan at the position of the camera from the following 3d data:
Camera (position and look direction)
An item which ...
0
votes
1answer
84 views
Making a 3D point cloud from multiple RGB-D images
I have multiple (4 kinect) cameras that give RGB-D (color and depth) information of the same scene from different points of view. I want to make a 3D point cloud out of these depth maps. I can get a ...
1
vote
1answer
312 views
What are the keywords to find an algorithm that detects embossed text from a 3d model?
Currently I am doing an acadmic research about an idea which came into my mind lately. I have a 3d model and I want to extract embossed text .. anyone knows any papers? or if it is already proposed? ....
3
votes
2answers
43 views
2D to 3D view conversion
I came across this demo by Fox sports:
https://youtu.be/N9SxFf5WCb0
Where they show a player's view in a 360 space. Very smooth and nice.
I was wondering how do they achieve it without any cameras ...
4
votes
3answers
709 views
Measuring non-planar objects in image
I'm working on a computer vision application (using openCV) and the goal is to measure the width of an object before/after it falls on a container. So after the fall its position will be random, ...
0
votes
0answers
8 views
Denoising 3D matrix
Are there any standard techniques I can use to denoise a 3D matrix?
I hope to apply something like simple SVD denoising methods (e.g., reconstructed the images with salient singular values) to a 3D ...
13
votes
2answers
20k views
How to compute camera pose from Homography matrix?
Say I use only one calibrated camera. From this camera, I get images A and B. I know the homography between A and B, computed through OpenCV's findHomography().
I know the pose (rotation matrix R and ...
1
vote
0answers
17 views
Projecting 3D point to 2D image coordinates
I am trying to replicate the projections of a 3D point to 2D using the pinhole camera model and the formula $x = K * [R|-RC] * X$, where $x = s\begin{bmatrix}
u\\
v\\
1
\end{bmatrix}$, $K$ is the ...
0
votes
0answers
30 views
Obtaining camera matrix for estimating shape of moving object
I have an object that is moving parallel to a stationary camera. I would like to use Structure from Motion or Shape from Silhouette to obtain the 3D points of the object.
For that, I need to obtain ...
0
votes
0answers
178 views
Mapping ring asteroids in Elite Dangerous by image processing
In the game Elite Dangerous, which is an online spaceflight-based sandbox game set in a procedurally-generated galaxy, one of the most profitable in-game occupations is mining commodities from ...
0
votes
0answers
54 views
3D reconstruction of moving object
I am pretty new to the field of 3D reconstruction and overwhelmed by the large amounts of different methods. I am trying to find the correct method for my use case:
Setting: I have a stationary ...
0
votes
0answers
24 views
Compute $d^2$ entries of a 3D convolution faster than $O(d^3)$
Let $A,B\in \mathbb{R}^{d\times d\times d}$. The 3D circular convolution $\text{conv}(A,B)$ can then be computed as $F^{-1}(F(A)\odot F(B))$ where $F(\cdot)$ denotes the 3D discrete Fourier transform ...
0
votes
0answers
7 views
Poisson Meshing without filling holes
Currently I have a point cloud coming from a single depth camera (Microsoft Kinect for Azure). In the resulting point clouds there are of course occlussion and gaps. I wanted to create a mesh from ...
0
votes
0answers
12 views
KCS - 3D profile representation
I was reading Character Recognition Systems book and in section 2-3-2-3 a new kind of filter is introduced (instead of normal Gaussian filter) to reduce mask size and to prevent data loss by the name ...
2
votes
4answers
2k views
Extending 1D window functions to 3D (or higher)
(cross post of SO: https://stackoverflow.com/questions/27345861/extending-1d-function-across-3-dimensions-for-data-windowing )
For the sake of image (volume) registration, I'd like to apply a ...
4
votes
1answer
2k views
How Can Convolution and Deconvolution be Defined for 3D Images?
I am trying to understand how convolution and deconvolution can be represented for 3D images/ stacks of data. I would prefer it, if you built the these concepts from 1D vectors to 3D matrices in terms ...
0
votes
1answer
52 views
why is it so hard to simulate up and down position on headphones?
i'm wondering how come simulating front,back,left and right source position on headphones is easy but up and down is not ? (maybe even impossible ?)
is it due to the shape of the ear ? but should we ...
0
votes
2answers
120 views
Generate 3D image from Multiple 2D Images
If we're to capture an image of a body using four (4) WebCam with a 16 megapixel (1 in the front, 1 in the back and 2 sides(left and right)). Is it possible to make a 3D out of it using image ...
1
vote
0answers
38 views
How to create 3D signed distance function?
I am trying to segment a 3D shape using levelset. I want to track shape movement in consecutive frames.
Now I want to create a signed distance function matrix for ...
0
votes
0answers
21 views
Switching camera angle based on several images
Given a number (3 or 4) of different images of a given subject from different angles, how do I interpolate to an angle that isn't available on any of the photos?
What is this technique called and is ...
1
vote
0answers
30 views
Bundle adjustment optimization parameters
While reading the Wikipedia article on Bundle adjustment, I came across the following objective function used to represent the bundle adjustment problem.
I have two questions regarding this objective ...
0
votes
1answer
271 views
Isosurfaces from three dimensional column data: methods
I have just been asked the following question, and I somehow felt short of smart answers. You are given a series of $N$ triplets of values ($P_1$, $P_2$, $P_3$), pertaining to physical measurements. ...
0
votes
1answer
386 views
Multiple-image dense point cloud reconstruction with camera extrinsics/intrinsics
I have the following data available:
Images from different angles
X, Y, Z, pitch, yaw, and roll for each camera/image, together with the timestamp
Lens distortion parameters and intrinsic camera ...
0
votes
1answer
220 views
Is it possible to generate depth map from graycode sequence without using printed calibration patterns?
In a camera-projector system, if only the camera's intrinsics are known, is it possible to generate the depthmap fully automatically through a graycode sequence without any manual calibration process (...
6
votes
3answers
4k views
The fastest way to “fill holes” in 3D?
I have a 3D binary image that I must fill all of the holes in the image.
"Fill holes 3D" in this case, is basically a 3D version of
BW2 = imfill(BW,'holes') from ...
0
votes
2answers
535 views
How can we combine 2D image with 3D image for the same sense?
We have 3D point cloud data captured by a laser scanner and need to register it with 2D images to get further information. In our case, the 2D image and 3D points are not overlapping and therefore we ...
0
votes
0answers
96 views
How to filter a sequence of frames?
I'm have a sequence of 2-dimensional MxN frames.
I have concatenated these frames to form a 3-dimensional MxNxT matrix.
Now i want to filter this 3D volume by 2 types of filters (a 2D log-Gabor in xy-...
0
votes
2answers
98 views
1D as a 3D FFT - what’s wrong here?
I implemented the algorithm to calculate 2D DFT derived from 1D DFT.
It works great, and makes my calculations much more efficiency then regular 1D DFT.
But now I want to make 3D DFT derived from 1D ...
1
vote
2answers
3k views
Camera calibration and extrinsic parameters for perspective transformation
I'm working in a photogrammetry camera and laser application where I need to measure a displacement in a specific plane, this is a quick diagram of the setup:
In order to get proper measurements I'm ...
0
votes
1answer
44 views
How left out down-sampling in 3D-DWT just on the Z direction
I am working on image processing by a 3D wavelet transform.
I have a problem with the classification size of the wavelet coefficients. As you know, when we apply 3D_DWT on the image (for example: ...
2
votes
0answers
2k views
3D image segmentation
Re-written more specific question
For the details of my segmentation algorithm, see the original question below.
I have managed to improve the segmentation considerably by using a different strategy ...
1
vote
1answer
1k views
Accelerometer - coordinate system transformation
I'm getting some accelerometer readings from an Android phone, but it comes in on the phone's coordinate system. I want to apply a transformation to put the acceleration in the world coordinate system ...
1
vote
1answer
688 views
Decomposition of **3D** structuring elements for morphological operations
I am struggling to implement a mathematical morphology toolset in an image processing package. I base my implementation on what I saw in MATLAB, and on several papers on the subject.
There seems to ...
7
votes
1answer
214 views
Minimization of Essential matrix
A problem in computer vision and 3d reconstruction is getting the camera's intrinsics parameters. A common solution is to use an object in which one knows the measurements of the shape before hand, ...
0
votes
1answer
96 views
Estimating exterior camera parameters by matching lines using least square estimations (Lowe, 1991)
I'm new to computer vision and graphics. I want to estimate exterior camera parameters using non-linear least square estimation as suggested by "Lowe, David G. "Fitting parameterized three-dimensional ...
2
votes
1answer
2k views
Triaxial accelerometer to single signal
I have some smartphone recorded accelerometer data, so I have acceleration along 3 axes: $$a_{x}, a_{y}, a_{z}$$
The accelerometer data was collected by securing a phone to a walking subject. I'm ...
0
votes
1answer
306 views
Why are two cameras mounted in paralle in stereo application?
For stereo cameras on the market, two cameras are always mounted side by side and with a displacement that is perpendicular to the cameras’ optical axes. I take this setup for granted. One idea came ...
0
votes
1answer
49 views
A PID that can handle 2 inputs for my application
I am currently working on a Drone that navigates to different points that it detects on the ground. To go from one point to another in a smooth manner, I am employing a PID looks at the error between ...
1
vote
1answer
770 views
Sensor fusion with accelerometer and gyroscope only
I need to track an object in 3D-space and I can use only accelerometer and gyroscope. I can't use a magnetometer because the object itself has a strong magnet.
I need to know the orientation of the ...
0
votes
1answer
783 views
Two-View 3D reconstruction using the sparse Levenberg–Marquardt algorithm
I have trouble implementing the Levenberg-Marguardt algorithm as described in the book Multi View Geometry in Computer Vision. To be more specific I have trouble calculating the partial derivatives ...
0
votes
3answers
101 views
What algorithms can automatically determine a 3D scene from one or a few 2D images?
For a project I'm doing, I'm trying to model a scene based on a phone camera's video input, and then insert arrows into it that indicate direction in three dimensions.
I've looked around, and this ...
0
votes
1answer
1k views
the position of image plane in optical imaging
In the book Learning OpenCV, there is one figure that show the image plane always is focal image.
The description of the figure from the book is as follow.
We begin by looking at the simplest model ...
1
vote
1answer
1k views
Backprojection of 2D image on 3D model
I am trying to implement the paper "Face Reconstruction in the Wild". In that I use a template 3D model and rotate it to align it with the orientation of the face in the 2D image. Now I want to ...
1
vote
1answer
178 views
Essential Matrix from line correspondences
I'm looking for some library with a function to compute an essential matrix from line correspondences in multiple images. All the computer vision libraries I know use point correspondences to compute ...
1
vote
1answer
472 views
Point cloud comparison
Let me preface this question with the fact that two hours ago I had no idea what a cloud point was. I do however have a solid mathematical background although geometry has never been my focus. I do ...
2
votes
2answers
81 views
How does google automatically create 3D cityscapes?
In the last years, Google models not only are major cities, but also suburban and rural areas (google video)
I read that there are some tridimensional model building algorithm here.
How could such ...
