Questions tagged [projection]

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What is the expression for intensity of Laser beam focussed at a point at an angle theta?

If the laser beam is focussed directly at a point then the simplified expression is: $$I_1(i,j) = 8\frac{P}{\pi d^2} e^{-\frac{8}{d^2}\left(x^2(i)+y^2(j)\right)}$$ If the laser is focused at same ...
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1answer
44 views

How to get general projection of rect function?

To be more clear I want to get a general expression for PƟ(t)= ∫∫rect(x)rect(y)δ(xcosƟ+ysinƟ-t)dxdy I also want to find particular projection for Ɵ=0 and Ɵ=45 and also Fourier Transform of the ...
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1answer
74 views

Transforming Non-Uniformly Sampled Image onto Rectangular Grid

I have an image and associated latitude and longitude matrices. So I know the latitude and longitude of every pixel. However, due to the camera orientation, the image is skewed and thus the latitude ...
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0answers
43 views

Offset Wall Color From Reflected Image

I have a movie projector which is projecting an image on a brown wall. The projector allows me to adjust 6 values. Red brightness, Green brightness, Blue brightness. Red contrast, Green contrast, Blue ...
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2answers
257 views

Projection Operator Related question

If P is a projection operator, show that I-P is a projection operator. Determine the range and nullspace of I-P. How can I solve this? What should be my approach?
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2answers
544 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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1answer
54 views

Why is this projection wrong?

I am trying to figure out why a 3D cube doesn't project in the right place in the image. I start with the camera at origin and the cube centered at (0,0,1) world ...
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0answers
21 views

Black “grille” after stereographic projection+rotation

When I do a stereographic projection and rotationX of omnidirectionnel image, I get this image: My question is why I get that "grille" in the image, it appears only when I add rotation
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1answer
38 views

scanning an image for projected points

I'm projecting a series of points onto a surface and then recording their locations in the corresponding image. However, if one goes pixel by pixel a single point may, at times, take up multiple ...
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3answers
687 views

Generate projection image by OpenGL or Matlab

I want to generate the "projection" image described as bellow. The left picture is the original picture and the right image is what I want. But, I have no idea about how to generate the right image. I ...
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1answer
2k views

Is it possible to hack camera calibration without having access to the camera?

Many times we have a stream of video to process without access to camera. Having access to camera matrix would be beneficial for various processing techniques. Is it possible to hack camera ...
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1answer
122 views

Image Projection with SIFT

Recently, I am thinking about a problem regarding image projection. I have a larger picture as bellow. I want to find the transformation matrix, x'=Hx. When the above image pass the transformation ...
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0answers
6k views

Radon Transform Implementation In Matlab

I know MATLAB has a built in Radon function, but I am working on implementing the radon transform in order to perform filtered back projection. As I started, my idea was multiple nested for loops for ...
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1answer
479 views

Fisheye lens calibration

I am writing a lens correctionion code and the process should do several things: Inverse fisheye projection to obtain rectilinear image Barrel/pincushion correction Vignetting correction Lateral ...