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# Questions tagged [3d]

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### Tracking vectors in 3D

A 3D object with smooth surface is given as in the figure. There exist two vectors $v_1$ and $v_2$ on different points on the surface. These vectors represent velocity vectors on different moments in ...
• 101
26 views

### 3D-to-3D pose estimation

Given a set of 3D points with their coordinates in 2 different coordinate systems, what is the correct algorithm to use in order to estimate the relative rotation and translation of the coordinate ...
• 11
17 views

### Get Length, Breadth and Width using Intel Real Sense Camera

I want to find 3d dimensions of an object in an image. With mobile phone camera and using the code here I can compute dimensions of an object within an image using a reference object. Following are ...
1 vote
11 views

### Finding optimal translation & rotation to place a 3d model into its visual hull

The title already sums up my question pretty well: I've got a pretty accurate 3d model of some object. This object is usually non-convex and it also may have some holes etc. This object is placed (...
• 11
153 views

### Filter 3D volumetric image with a Butterworth filter in Python

I have been looking for a way to filter a 3D volumetric image in python with a Butterworth filter, but I haven't found any good solution. I have tried this: ...
16 views

### What is the name of the filter or technique to reduce depth aliasing around object edges when working with camera depth?

I'm working with a point cloud, created by sampling a 2D camera texture and a depth map. The color is combined with the depth and is projected onto a 3D scene to create a "point cloud". The ...
• 315
204 views

### HRIR interpolation using VBAP

1) Problem description I am trying to implement a 3D audio simulator in Python. I am using the HUTUBS dataset as HRIR database (more informations here: https://depositonce.tu-berlin.de/handle/11303/...
1 vote
38 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 ...
• 111
1k 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 ...
76 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 ...
• 183
1 vote
141 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 ...
772 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 ...
• 109
1 vote
85 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 ...
28 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 ...
75 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 ...
• 121
72 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 ...
• 79
1 vote
56 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 ...
• 477
1 vote
55 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 ...
• 111
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
38 views

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 ...
• 149
611 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. ...
• 29.7k
570 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 ...
• 111
292 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 (...
105 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-...
• 477
151 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 ...
• 329
1 vote
5k 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 ...
• 37
46 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: ...
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 ...
• 121
104 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 ...
• 103
3k 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 ...
• 285
50 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 ...
• 211
453 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 ...
• 343
1 vote
810 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 ...
• 13
854 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 ...
• 15
2k 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 ...
• 343
105 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 ...
• 101
1 vote
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 ...
• 113
773 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 ...
1 vote
480 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 ...
154 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
96 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 ...
• 123
1 vote
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 ...
• 285
1 vote
58 views

### How to reconstruct 2D flat image from a series of pictures of a tube

I have pictures of an oesophagus (ie a tube) taken under standard white light looking down the tube. I have about 10 images taken over 20cm in series. The image looks forward down into the tube and ...
721 views

### Image distortion and alignment on 3D mesh / pointcloud

Currently I have a fairly accurate (50 µm) and large dataset from a 3D scanner and a set of high resolution pictures. Sadly the 3D scanner (a Nikon/Metris arm-based CMM that was hanging around the lab)...
• 103
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 ...
• 211
1 vote
219 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 ...
• 111
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### Smoothing 3D Data for the Second Derivative

I am not a signal processing expert and my feeble attempts at solving this problem have come up short. I have a C++ application which is being fed regularly-spaced (in time) 3D position samples. The ...
• 143
1 vote
68 views

### neural network for 3D pictures

I'm wondering if they are some state-of-art algorithms to apply the convolutional neural network approach to 3D pictures, eg. input is no longer a grid of pixels, but voxels. My objective is to ...
• 11
1 vote
105 views

### Sensor Data Fusion with Orientation Sensors in 3D Euclidian Space

Preconditions For measuring the position of a mobile device in 3D space, I utilize two sensors with different characteristics that measure device orientation. Sensor A (a combined sensor of ...
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856 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 ...