# 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, ...
• 75
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 ...
• 172
1 vote
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 ...
• 111
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: ...
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 ...
• 1,447
1 vote
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. ...
• 143
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 ...
• 131
1 vote
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 ...
• 11
1 vote
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" ...
• 111
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 ...
• 33
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 ...
• 171
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 ...
• 11
72 views

### 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 ...
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 ...
• 492
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 ...
• 229
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, ...
• 229
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 ...
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 ...
• 95
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 ...
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. ...
• 53
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: ...
• 603
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 ...
• 1,689
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 ...
• 273