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Questions tagged [3d]

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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 ...
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1answer
27 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. ...
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1answer
42 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 ...
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1answer
67 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 (...
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43 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-...
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300 views

Plot CWT (Continuous Wavelet Transform) in 3D using Python

I am working on a project using signal processing. Part of my work is to apply the CWT on the signal I have. As I read, that I can plot the signal in the frequency-time domain using CWT. So my ...
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32 views

correspondence problem in multiple views

I have a setup with $n$ cameras $\{P_i \}_{i=1}^n \in \mathbb{R}^{3\times4}$ and $m$ 3d points $\{X_j \}_{j=1}^m \in \mathbb{P}^3$. The 'ideal' set of 2d points for each camera can be defined as $\big\...
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2answers
47 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 ...
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2answers
1k 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 ...
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1answer
30 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: ...
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1k 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 ...
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2k views

Get the correct solution for rvecs and tvecs for camera pose estimation, using SolvePnP in OpenCV C++

I am trying to measure the pose of a camera and I have done the following. Mark world 3-D(Assuming z=0, since it is flat) points on corners of a square on a flat surface and assume a world coordinate ...
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1answer
87 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 ...
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1answer
800 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 ...
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1answer
42 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 ...
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1answer
109 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 ...
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1answer
599 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 ...
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1answer
639 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 ...
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1answer
721 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 ...
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3answers
98 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 ...
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1answer
644 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 ...
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2answers
275 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 ...
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1answer
374 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 ...
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2answers
104 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 ...
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2answers
74 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 ...
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0answers
98 views

Point cloud color blending after registration

I have succesfully registered two point clouds of the same scene obtained from different camera positions. Color values are different due to changes in light condition between both positions. I would ...
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1answer
867 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 ...
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0answers
44 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 ...
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2answers
419 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)...
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0answers
39 views

Retrive texture / data from photos of sphere object

I've built a photo box for taking photos of spherical objects (balls etc). I take photos cubical from six different angles. Now I want to extract the bitmap texture from the object with most ...
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0answers
45 views

Creating a 3D model continuously from Video Feed

So I had an idea which might make it into a University project,thing is I don't know how to search for it,don't know some of lingo. Basically I need to find a way to transform a video feed into a 3d "...
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1answer
91 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 ...
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1answer
268 views

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 ...
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1answer
60 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 ...
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0answers
84 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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1answer
454 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 ...
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0answers
531 views

Distinguish between 2D and 3D objects according to depth

I'm trying to distinguish by code between a real 3D object and its picture - a 2D object, based on depth information. However the picture (= the 2D image) might be captured from noisy background, so I ...
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3answers
588 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, ...
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1answer
102 views

Is there any research work on the possible data structures that can be used to represent an architectural design of a building? [closed]

I am looking for a data structure, that can be used for description of a floor plan of a building. Its not about the format, I am asking about any other way to describe the floor plan of building, ...
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1answer
265 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? ....
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2answers
1k 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 ...
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0answers
868 views

Autocorrelation and FFT : avoid zero-padding

Some posts evocate the computation of convolution or cross-correlation using FFT and zero-padding the temporal signal. I want to compute the autocorrelation of a 3D array using FFTW (2 dimensions are ...
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1answer
157 views

Beyond cross-eyed 3D (VR application)

Making static 3D image is very simple - we just take image pair with something like this: then we can see 3D image by putting the left and right eye image side by side and crossing eyes or ...
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3answers
3k views

Is it possible to convert from 2D to 3D form?

I have captured car positions at different frames from the video. Suppose car's(e.g.left side car which is coming towards us in the images) centroid at video frame1 is P(x1,y1) and Q(x2,y2) at video ...
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2answers
453 views

How to get a generic 3d Face model?

I'm working on image processing that involves facial features. Where can I get a generic 3D model of a human face? (any format is fine as long as I can manipulate the data using C or Matlab)
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1answer
634 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 ...
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2answers
778 views

Getting HRTF from 3-D scan + acoustic simulation

This question follows from Modelling propagation of sound wave by particle simulation This last fortnight I have started experimenting with Binaural audio; it really blows everything else out of the ...
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0answers
117 views

Upsampling Methods for Computed-Tomography

I have two sets of data of given Field of view, one of them only covers a subset of the FOV of the other. I therefore want to upsample the one with the larger FOV to combine it with the other one. So ...
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0answers
40 views

How to detect directional signal in three dimensions?

I have three orthogonal accelerometers that give accelerations in x,y and z dimensions. I'm trying to detect directional vibrations between certain frequencies. In other words, my input is 3d vector ...
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1answer
234 views

3d CT segmentation

It's my first attempt at 3D analysis. I am trying to segment a 3D CT data. My case study is very simple: trying to segment circular objects in my data. Do you have any suggestions on how to achieve ...