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1500 questions
5
votes
1 answer
inside and outside region identification from 2D contour
A 3D model is sliced against a plane and the resulting 2D contour is projected onto the plane. I am looking for an efficient algorithm to identify the inside and outside region of the contour. Simultaneously I need to identify outer and inner loops…
sajis997
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5
votes
1 answer
Sine-based Tiled Procedural Bump
I am trying to implement this formula to generate bump but I am facing some issue. The result doesn't look the same it's much darker.
Here is my result (without same parameters) but it is much darker and I don't get why.
And here is the associated…
MaT
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5
votes
2 answers
Path tracer not rendering shadows
I am trying to implement for research purposes a gradient-domain path tracer. In order to achieve this step I first need a working Path tracer. I have been creating one so far but results are wrong and I will explain you why. Some concepts:
I am…
Tarta
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5
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1 answer
Why does the integral of NDF over a solid angle equals the area where micronormals belong to that angle?
In Understanding the Masking-Shadowing Function in Microfacet-Based BRDFs, Section 2.2, Mr Eric Heitz defines the distribution of normals as:
And then, he goes on with the following assertion:
I fail to understand how can D have such a property.…
wip
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5
votes
1 answer
Gpu derivatives. How it's done across 2x2 boundary?
This question bothers me since the first time I got to know about derivatives in pixel shader. Suppose we have a 2d texture:
5 10 20 30
6 11 50 100
If I correctly understand, the derivatives for the pixel [0, 0] will be:
dx = pixel[1, 0] -…
nikitablack
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5
votes
1 answer
Which interpolation algorithm does MS Paint on Windows 7 use for image rescaling?
I was about to scale this image down to 64x64 pixels:
The result I got on MS Paint on Windows 7 was surprisingly good (i.e. crisp edges):
, whereas scaling it with GIMP resulted in for cubic and for Lanczos3 interpolation, both of which look…
dialer
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- 2
5
votes
2 answers
What are the current open problems in Computer Graphics?
I did a quick investigation about the topic but there doesn't seem a decent resource to find related problems without digging into latest CG papers (unlike CS problems you can easily find a Wikipedia list)
With open problems I mean phenomenas that…
concept3d
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5
votes
1 answer
How to convert Non-Axis Aligned Bounding Boxes to AABB
I am trying to write a ray tracer to render boxes that are arbitrarily rotated, i.e. not necessarily axis aligned. While I am reasonably comfortable ray tracing axis-aligned bounding boxes (AABB), I don't know how to handle non-axis aligned objects.…
Newb
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5
votes
1 answer
Can I run polygon insetting on the surface of a mesh?
I have a set of closed loops on the surface of a non-self-intersecting triangle mesh, and I need to create inset versions of them on the surface of the mesh. In other words, I want to generate a straight skeleton from them.
Within each single…
Nick Parker
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5
votes
1 answer
Should not specular reflection on a rough surface be similar to diffuse reflection?
Different BRDFs are usually used to compute diffuse and specular reflection.
Some of the most often used include for example the Lambert BRDF for diffuse reflection and the Cook-Torrance BRDF for specular reflection.
Cook-Torrance BRDFs are…
wip
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5
votes
0 answers
OpenSCAD Hull/Minkowski function by hand?
I am trying to model an organic object using OpenSCAD. However this will need to be ported over to older software. This restricts the primitives I can use (only cone, cylinder, torus, sphere and cubes) and the operations I can perform (difference,…
RCountZero
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5
votes
1 answer
Modern Screen Space Ambient Occlusion Techniques
Down the road, I'm planning to implement one or another GPU based ambient occlusion technique. My goal will be to approximate a physically based offline renderer, so I was pretty happy when Wikipedia led me to Approximating Dynamic Global…
user2500
5
votes
1 answer
Multiple Importance Sampling with more than one light
(Note: This has been cross posted from my ompf2 post.)
Recently I've implemented Multiple Importance Sampling for the sampling of surfaces in my ray tracer. I do this by, on each intersection, sampling both a random direction from the BRDF and also…
yuriks
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5
votes
1 answer
Seamlessly transitioning between nearby environment maps
I'm wondering what is the best way to achieve an effect like here: https://matterport.com/try/ when the camera is traveling between points in space.
Apart from simple color crossfade there seems to be some sort of perspective reprojection giving the…
MasterM
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5
votes
1 answer
SVG opengl implementation - strokes overlap on transparency
I am trying to implement svg rendering by opengl using meshes.
In paths with opacity less than 1, the color of overlapping strokes add up.
But it should be like this
the opengl calls are:
glDepthMask(false);
glEnable(GL20.GL_BLEND);
…
user3902333
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