Questions tagged [normal-mapping]

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Is it possible to reduce aliasing in derivatives used to estimate normals from a texture?

I am generating a normal map for a texture for use in a PBR shader. I have a map for the diffuse texture, and I am estimating the normal at each point using the derivative of the texture's brightness....
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0 votes
1 answer
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Bump mapping WITH precomputed tangents?

Most bump mapping (meaning black and white height map) uses Tangents/Bitangents computed from Position using dFdx/y. And they also compute the offsets/derivatives of the height map using dFdx/y. The ...
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1 answer
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How do I convert Derivative Maps to Normal Maps?

I recently came across a set of models that include Derivative Maps. I'd like to use them in Blender, but from what I've seen so far Blender only supports exporting baked Derivative Maps, not ...
1 vote
1 answer
68 views

Is orthonormal tangent space an industry standard for use of tangent space normal maps?

I'm investigating software that uses the unnormalized, interpolated vertex normal for creating its tangent space, creating a scaled tangent space that depends on concavity/convexity of the mesh. It ...
0 votes
1 answer
92 views

Why do normal maps perturb existing normals as opposed to 'overwriting' them?

To preface, I am a bit of a beginner to graphics programming. From what I've read, normal maps merely perturb the existing surface normal as opposed to overwriting them as I'd previously thought But ...
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1 vote
2 answers
163 views

How are the normals 'derived' from grey scale bump maps?

From what I understand, grey-scale bump maps are used to perturb normals on a surface such that the surface appears to have bumps. With a regular tangent normal map, it seems relatively intuitive ...
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1 vote
0 answers
72 views

Normal mapping should affect specular reflections?

I'm asking this question on behalf of a friend so can't provide any images for now. The problem is to simulate a car paint material with some flakes or graininess in it. This is first done in blender ...
0 votes
0 answers
84 views

Help me understand the derivation of this tangent space to object space matrix

I was trying to follow this http://foundationsofgameenginedev.com/FGED2-sample.pdf But had problem understanding formula 7.33. $$p_i-p_j=(u_i-u_j)\mathrm{t}+(v_i-v_j)\mathrm{b}$$ * $p_i,p_j$ being ...
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3 votes
1 answer
627 views

How to draw surface normals from surface normal maps?

Using deep learning to estimate surface normals from monocular RGB images is a common task. The resulting image generally looks like this: My question is how can I use this map to actually draw a ...
2 votes
1 answer
275 views

How do you apply a normal map to a 3d mesh?

I'm writing my own mesh renderer, and I previously was able to apply a normal map to a sphere, so I understand the basic process of applying a normal map. But my understanding is that in order to ...
2 votes
0 answers
53 views

Normalization technique to increase spread of data in rgb space

I am visualizing a dataset. My technique is to encode the data into a rgb image with the channel range [0, 255]. The data clusters in a narrow range relative to [0, 255], however, so I'm not getting ...
1 vote
0 answers
78 views

Problem calculating tangent space

I am currently writing a 3D rendering engine for educational purposes. In general everything is working except that I am chasing down a problem in my cube mesh / tangent calculations that I can't find....
1 vote
2 answers
898 views

Calculate normals from vertices

Assume you have a list of vertices and their connectivity information. (I.e you can find all the adjacent edges and faces to each vertex). What is a good approach to calculate a normal from this ...
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1 vote
1 answer
793 views

What is a 0 "null" normal map? Or Unlit shader

Does anyone understand normal maps and what would color a uniformly 0 normal map be? I'd like to convert a standard shader into an unlit shader, so (I think?) the idea is that the normal map should ...
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2 votes
1 answer
125 views

Normal Map Storage (Not Unit Length)

Looking at various assets (models / textures / scenes) available online, I have noticed a trend that conflicts with my assumptions. Many of the normal maps contain texels whose vector length deviates ...
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1 vote
1 answer
80 views

Wrapping normals around a sphere

I'm using a vertex shader to effectively wrap vertices on a sphere. Starting with world_position already after multiplying the vertex by the model transform matrix ...
1 vote
1 answer
5k views

What is the difference between world coordinate, viewing coordinate and device coordinate in computer graphics?

The 2D pipeline involves with the construction of world coordinate scene followed by converting world coordinate to viewing coordinate, then transforming viewing coordinate to normalized coordinate ...
2 votes
0 answers
501 views

Recreate geometry from normal map

I have a group of low polygon meshes, with associated normal maps. The normal maps were created by baking from high polygon meshes, which I no longer have access to. Is it possible to recreate ...
2 votes
1 answer
79 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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2 votes
1 answer
78 views

Finding the normals of a tileable 2D surface extracted from 4D space

If I use a 4D noise function which returns a noise value and a four-part analytically derived gradient vector, I can create a 2D tile which is seamless (i.e. the opposite edges match) through ...
0 votes
1 answer
82 views

How are the three plane equations derived in the NVIDIA's CG Tutorial chapter 8?

I'm reading the chapter 8 of the Cg tutorial and I could not understand 8.4.1 : Because all these coordinates lie in the plane of the same triangle, it is possible to derive plane equations for x, y, ...
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1 vote
0 answers
300 views

Normal Artifacts On Grazing Angles

I am currently experiencing a very obvious artifact that occurs when looking at objects on very grazing angles Here is a picture of the artifact: I noticed that the issue was coming from my ...
4 votes
1 answer
2k views

How to compute normal of surface from implicit equation for ray-marching?

I want to represent ovaloids with ray-marching. I have ovaloids defined with an implicit equation. For instance, we can consider the equation of an ellipsoid given as: $$ \frac{x^2}{a^2} + \frac{y^2}...
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2 votes
1 answer
3k views

How do I build my tangent space matrix?

I'd like to understand how the process of building the "tangent space" matrix for normal mapping works. I'm following several tutorials, and other stackexchange questions, but I'm unfamiliar with the ...
3 votes
2 answers
252 views

Inconsistent shading in pathtraced image

I am currently building a pathtracer, which has support for vertex normals and face normals. There seems to be an issue when it comes to rendering objects with triangles exported from Blender. ...
1 vote
1 answer
467 views

How do you implement perspective correct Gouraud shading across a triangle?

What's the algorithm for doing so? I have flat shading working and I have perspective correct texture mapping working. Is the way your raster Gouraud shading much different from the perspective ...
2 votes
2 answers
3k views

Inverse-Transpose of Vertex Normals

For the past month, I have been learning on my own and writing a little graphics library and am currently working on the transformation of vertex normals to soon support lighting/shading. I understand ...
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4 votes
1 answer
3k views

Compute sphere tangent for normal mapping

I'm implementing normal mapping on my toy pathtracer. I need to compute the tangent (and bitangent) of any sphere point in order to create the matrix that will transform tangent space to world space. ...
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3 votes
1 answer
2k views

Correct way to set normal strength

I am working on a normal mapping. I need to have the ability to scale normal vectors to adjust the normal strength of the surface. Currently the way I am doing it basically shows plausible results. ...
2 votes
2 answers
1k views

Extract visible vertices from a 3D geometry model

Let's assume we have a 3D model consisted of XYZ-formatted vertices (such as point cloud model). My problem is given the position and normal of camera or camera ...
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4 votes
1 answer
458 views

How are Normal Maps created?

How does one go about taking a single photograph, like a picture of a rock wall, and getting a decent normal map out of it? If you can, I'd like to learn about the mechanics behind it, and not a ...
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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4 votes
2 answers
960 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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7 votes
2 answers
695 views

Does normal mapping make sense for a view of earth from space?

I am working on a planet visualizer, which at this point is little more than the NASA blue marble image applied as a diffuse texture. For the atmospheric rim, I am simply blending in a constant color ...
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13 votes
2 answers
3k views

Derivative maps vs. Tangent Space Normal maps

I discovered that some engines use derivative maps instead of tangent space normal maps. After some reading, it seems to be a really awesome way to replace tangent space normals but are there some ...
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3 votes
1 answer
127 views

NormalMap problems: bumps work, but shade does not

I've been trying to figure this out for a few days now, but I just can't get it right. I've read multiple tutorials and possible explanations, I even watched a java tutorial without finding the ...
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7 votes
0 answers
2k views

Bump mapping a ray-traced sphere

I'm attempting to apply a height map to a ray-traced sphere. The height map is stored as a texture. I have the intersection point on the sphere $p$, and I compute the normal vector at that point $N = ...
7 votes
2 answers
570 views

Sampling against geometry normals

I am writing a basic raytracer and have implemented normal maps. However, when using normal maps, sometimes the rays generated are opposite to the surface's geometry normal, so that the rays are ...
4 votes
0 answers
167 views

How is glint rendering done in Ray Tracing?

How is glint rendering done with ray tracing in the photo below? Is it just a simple normal map? I found a paper online that describes the exact same method used in the photo above but I have no ...
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12 votes
1 answer
15k views

Programmatically generating vertex normals

I'm working with Kinect face api, it provides an array of vertices and indices for triangles which is to be rendered to make the face image. The no of vertices and their order in array as well as the ...
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4 votes
2 answers
2k views

Screenspace Normals - Creation, Normal Maps, and Unpacking

I'm trying to condense my Deferred Rendering G-Buffer. So I have some questions about getting 2-component Screenspace Normals. I know Frostbite and Killzone (the only two AAA company's G-Buffers I ...
2 votes
1 answer
1k views

How to blend World Space Normals

I am trying to blend two world space normals inside a shader. One comes from a tangent space normal map converted into world space using a classic TBN matrix and the other one is a mesh normal map in ...
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5 votes
1 answer
232 views

Image based lighting, tangent space coordinates, and optimization

When I saw an implementation of normal mapping that computed the TBN matrix in the vertex shader and converted everything (in particular the view vector and light vector) to tangent space at that ...