Questions tagged [mapping]

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Confusion about HDR image pipeline

I am working on a path tracing renderer, and I want to produce an sRGB image out of the HDR image buffer I get at the end of my rendering algorithm. Up until now I have worked just by clamping values, ...
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  • 75
2 votes
1 answer
91 views

Deriving formula for perspective correct interpolation

I am trying to derive the formula for perspective correct texture interpolation on my own while implementing my own software rasterizer (projecting an arbitrarily rotated triangle in camera space on ...
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  • 172
1 vote
1 answer
62 views

How to map texture pixels to the corresponding 3D positions?

I have a mesh stored in .obj format with a texture image in .png format. For any "defined" pixel in the texture image, I'd like to compute the corresponding 3D coordinates when the texture ...
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  • 111
3 votes
1 answer
2k views

Tone Mapping vs Gamma Correction

There is something about these concepts I'm not understanding. I thought the point of gamma correcting images is to make sure that the values in linear space map correctly when displayed on screen: ...
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2 votes
1 answer
86 views

Controlling "zoom" and "position" of a cubemap in shaders

I am trying to mimic reflections in image composition using shaders. I have gotten this far: In this image the floor is "reflecting" the back wall, however the reflection is uncanny because the ...
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1 vote
1 answer
986 views

convert image pixel dimensions to UV

Hi i am rather new to computergraphics but i am trying to map an equirectangular image (360 video) to the inside of a sphere now i found the following formula to do this. ...
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2 votes
1 answer
75 views

How is this normals map supposed to work?

I have come across this image that's labelled a bump map to be used with a 3D model. It looks like this: In this map, which is an RGB map, it seems we have pixels whose normals face upwards shaded ...
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  • 131
1 vote
0 answers
753 views

Why do perspective correction based texture mapping do depth division

I'm currently trying to understand how works perspective correction texture mapping. I saw that actually it works by interpolating the z value of the three point of the triangle which the current ...
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  • 11
1 vote
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54 views

Convex hull around polygon for cave mapping

For the purpose of mapping caves, we survey new passages so that we take main polygon (survey from point A to point B) and on each "node" (survey station A in example), we shoot multiple "splay shots" ...
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3 votes
1 answer
1k views

How do I convert a hit on an infinite plane to UV coordinates for texturing in a Raytracer?

I am trying to convert a ray hit on an infinite plane, defined by an origin and a normal vector, into UV coordinates, so I can find the appropriate texel at that point. Code I have is close to ...
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  • 33
0 votes
1 answer
4k views

What is mipmapping?

I know OpenGL likes the texel resolution of textures be some power of 2 in each direction because of mipmapping. (They say that this is not a totally stringent condition, but it is preferred) Can ...
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  • 171
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1 answer
738 views

Tone mapping bright images

I am rendering the sun in an image, and the sun comes out white and is basically very unrealistic. I have tried searching for tone mapping algorithms but I'm very lost. Can someone guide me to do ...
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1 answer
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I need to build my own map renderer

I have OSM world data (essentially I processed the XML data into JSON containing arrays of objects (streets, buildings etc.) that each are represented by an array of lat/lon coordinates). Some of ...
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4 votes
1 answer
60 views

Is there a term for mapping between two arbitrary quadrilaterals without using homography / perspective projection?

When warping the contents of an arbitrary quadrilateral to another by extrapolating equal points along both the "lengths" and "widths", thus ignoring all perspective effects / foreshortening, we are ...
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3 votes
1 answer
1k views

Rotation matrix for a 3D object in space

This is the follow-up question from here: Minimum requirements to uniquely represent a 3D object in space Assume I have 3 original points in a 3D object (in 3D space) as ...
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  • 229
4 votes
2 answers
909 views

Minimum requirements to uniquely represent a 3D object in space

Let's assume we have a 3D object (in 3D space). We get a single representation vertex from this whole 3D object. Given the fact that the object can be moved and rotated in the space in any direction, ...
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  • 229
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1 answer
277 views

Getting texture value of cartesian coordinate from a Obj file

I have an obj file together with an associated mtl file and texture jpg file. I have managed to find some code that sets a specific camera view and raytraces the image to output a depth map plus a ...
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3 votes
2 answers
551 views

Texture Mapping jagged pixel edges

I'm currently writing a software renderer. I managed to implement texture mapping and it works fine. Only issue is, that the edges between the pixels are sometimes jagged in x direction as you can see ...
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8 votes
1 answer
4k views

Perspective Correct Texture Mapping

So I'm trying to correctly map my textures in my software renderer using the u, v coordinates but I can't seem to get it working. I got affine texture mapping working. This is what I can produce using ...
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5 votes
1 answer
357 views

The Process of Spherical Harmonics

I have read about spherical harmonics from Here about the usage of SH for generating Irradiance Environment Maps and how it can make the process of generating EM faster than the regular operations. ...
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13 votes
2 answers
9k views

What is an index buffer and how is it related to vertex buffers?

I have a vertex buffer like this: 0.0, 0.0, 1.0, 0.0, 0.0, 0.6, 1.0, 0.6, 0.5, 1.0 I have the following index buffer: ...
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  • 603
3 votes
2 answers
811 views

Why map Hammersley 2D set's (u,v) to sphere's (θ, φ) coordinates (and not to (φ, θ) )?

As explained in Holger Dammetz page Hammersley Points on the Hemisphere, the 2D coordinates (u,v) are usually mapped to the spherical coordinates (θ, φ). As a result, the coordinate "uniformly ...
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3 votes
1 answer
2k views

Uniform Buffers: What is quicker?

So I want to render a buttload of quads by using a single 4 point vertex array and change the position of the quad. What is quicker: Using glBufferSubData to ...
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  • 273
2 votes
1 answer
5k views

What algorithm(s) are behind Google Street View's 3d mapping mode?

I recently noticed that in some locations you could switch to a 3d mapping mode in Google Street View. Which algorithm(s) did they use to generate the 3d models of the streets? I assume it was more ...
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