All Questions

Filter by
Sorted by
Tagged with
0
votes
1answer
4 views

How is orthographic projection used in computer graphics technically classified as a projection?

I'm wondering why the orthographic projection we use in computer graphics is called a projection, if all it does is just scale and translate a mesh? According to wiki orthographic projection is ...
1
vote
0answers
14 views

Perspective correct interpolation z-buffer

While I was deriving expressions for perspective-correct linear interpolation on triangles, I reached the conclusion that the interpolation may be kept linear only if view-space $Z$ is available. ...
2
votes
0answers
42 views

The ploygon width parallel to the x axis as a function of the y ordonate?

Considering a polygon with n vertices as input. I need to calculate the integral of the form \[\int_A p(y) dA \] where $p(y)$ is a piecewise polynomial function of $y$. May be if I could find the ...
1
vote
0answers
35 views

How to scale signed distance field fonts properly?

I have a setup where I'm rendering a bunch of characters on a canvas with an SDF font. The users can zoom in to see the details of the smaller texts, but currently the smaller characters are quite ...
0
votes
0answers
21 views

Interactive point cloud

I’m trying to build an interactive point cloud renderer in Panda3D. I want to render a point cloud and be able to select a group of points and change their colors, maybe with a rectangular selector or ...
1
vote
1answer
28 views

Fast and exact Geodesics on meshes, Backtracking confusion

The following is an excerpt from a 2005 paper on geodesics on triangular meshes, taken from section 3.5 In this case $p$ is a point on some arbitrary face in a mesh, $p'$ is a point on one of the 3 ...
0
votes
0answers
27 views

Compose ViewMatrix and ProjectionMatrix

As the title says, you are able to compose the ViewMatrix and the ProjectionMatrix into one instead of multiplying a vector by the individual matrices. Instead of doing this at run time for each item: ...
2
votes
1answer
45 views

Which perspective projection matrix to use

I've seen two diffrent perspective projection matrix being used but i want to know which one of these are the best i think that they both output the same but i'm not sure so if anyone can help me ...
1
vote
0answers
44 views

OpenGL/D3D11 offscreen render multiple buffering

Recently I've been looking at Vulkan, and one thing that I noticed is that the application is responsible for choosing which buffer to render to in the case of multiple buffering. This got me thinking:...
4
votes
1answer
84 views

Reducing artificial rings in mean curvature of mesh

I have an isosurface/mesh (generated via marching cubes) of a micro-CT scan. Originally the surface looks very noisy, which becomes prevalent when the mean curvature is visualized: To reduce the ...
2
votes
1answer
89 views

Dynamic Ray-Triangle Intersection

I am working on a small simulation software which has a 3D Renderer that is using OpenGL. I render objects to the screen as triangle meshes. To be able to select the triangles on the screen, I have ...
0
votes
1answer
43 views

Probability density for explicit light sampling

When implementing explicit light sampling, I am separating the monte-carlo approximation to two parts $$\frac{1}{N+M}(\sum^N \text{direct} + \sum^M \text{indirect})$$ $$\text{direct} = \frac{\text{...
0
votes
0answers
22 views

MMP Geodesic algorithm I need clarification

I am reading the 1987 paper on Geodesics on polyhedra and I am confused on something. The paper states: If $I1==NIL$, the channel is simply that part of $f’$ to the left of $\beta_2c_2$; and if $I2==...
2
votes
1answer
64 views

Can the framebuffer in OpenGL jargon or its color buffer end up being the one and the same memory location as the one scanned by a display controller?

My understanding is: the 'framebuffer' in OpenGL is a collection of buffers: many (due to swapping or stereo rendering) color buffers, (only one?) z-buffer and (only one?) stencil buffer; each OpenGL ...
1
vote
1answer
65 views

How do you loop through the contents of a buffer in DX11?

Okay, so I'm currently using the IAGetVertexBuffers() method and I'd like to loop through some of the returned buffers to verify the contents. However, I'm kind of new to DirectX and C++ in general. I ...
2
votes
1answer
80 views

Transformations and change of basis in CG

Sometimes in CG literature a transformation is equated to a coordinate system change. This is fine as long as the transformation includes only a rotation and a translation. When scaling is involved, ...
3
votes
2answers
79 views

BRDF that interpolates between diffuse, glossy and reflective?

Is there a way to obtain a parametrized BRDF that smoothly interpolates between diffuse, glossy and mirror? For example, $\lambda = 0$ would be perfectly diffuse, $\lambda=0.5$ glossy and $\lambda = 1$...
1
vote
1answer
45 views

Finding geodesics on a mesh?

What are some state of the art methods/algorithms to find geodesics on arbitrary manifold meshes?
1
vote
0answers
72 views

Why does my self-written rendering engine make further away objects look larger?

I am writing a very simple rendering engine. I have already made a few tests, but somehow the images it creates look wrong. Objects that are further away from the camera look larger than objects ...
0
votes
0answers
17 views

Open GL mapping/hash function on hexagon grid, translating from a cell ID to pixel location on 1d texture

I've spent the last three days trying to figure this out, my intuition about this space has been thrown out of the window. The problem is this: I have a hexagon grid making function that returns an id ...
2
votes
1answer
48 views

Rendering moist/wet materials like human anatomies for surgical simulators

Real human anatomies look wet/ moist when operated. I am looking for some good methods for rendering anatomies in a virtual simulation, and hence I have done a literature survey on 'Rendering wet ...
3
votes
1answer
61 views

Are some 3D objects “solid”? Do they have internal density? If so, when, and in which file formats?

I am more or less a complete novice in the field of 3D modeling. I understand the basics of a polygon mesh and a texture; however, it was always my understanding that 3D models were, effectively, &...
4
votes
0answers
66 views

Performance of Compute Shaders vs. Fragment Shaders for Deferred Rendering

I have written a deferred renderer that can use either a fragment shader or a compute shader to execute the shading pass. Unfortunately, the compute shader implementation runs slower. I'm trying to ...
1
vote
1answer
57 views

How to unproject cursor with orthographic projection

With perspective projection we can unproject screen space coordinates of the cursor to the near and far plane of the frustum and calculate the direction of the ray through the cursor. ...
1
vote
1answer
27 views

DXC error when compiling PSO

I am trying to compile some really simple shaders with DXC but, when creating PSO, I get: ...
1
vote
1answer
23 views

Is there a general rule with regard to using the inverse of the “camera” to world when using a homogeneous transform matrix?

Not sure if this is just specific to this article but it says: We learned how to convert points from world to any local coordinate system. If we know the local-to-world matrix, we can multiply the ...
0
votes
1answer
55 views

How to display an in-memory framebuffer

I'm planning to write a small software rendering engine (before anyone asks, it's kind of a learning/scientific experiment for me). Before writing any code, I'm already stuck at the very first step: ...
0
votes
0answers
31 views

Confusion about the concepts of “constraint-based” and “impulse-based” for rigidbody simulation

Thanks a lot for your attention to this question in advance! It is my first try to ask for help on this amazing StackExchange. If I do something inappropriate, please point it out directly so that I ...
3
votes
2answers
149 views

Why are texture coordinates often called UVs?

Is there some historical reason texture coordinates are often called UVs? I get that vertex positions are x, y, z but even OpenGL has TEXTURE_WRAP_S and ...
4
votes
1answer
82 views

How to compute the following integral over a polygon?

I am implementing an algorithm which requires me to compute the following integral, $$\int_{Poly(P_i)}||P-P_i||^2 dP$$ where $P_i=(X_i, Y_i)$ is a point in 2D and $Poly(P_i)$ is a polygon containing $...
1
vote
0answers
29 views

Principal component analysis on 3d points and other ways of capturing variance

So, I would like to do capture on 3d pointclouds of 3d models the planes/vectors where for each object we have the highest variance (i.e. for object represented by 2000 3d points I would like to get ...
5
votes
1answer
463 views

How does UV unwrapping work?

I would like to project the triangles of my mesh to a 2D surface. I would like to minimalize the distorion, avoid breaking connected polygons if possible, and also maximalize the used space on the 2D ...
2
votes
0answers
46 views

Accelerating dose calculation for a radiation therapy planning system

During radiation therapy, appropriate radiation is fired from various positions around the patient. Radiation therapy planning determines the values of the radiation at various positions. This ...
0
votes
1answer
36 views

Closest sphere on segment

I am trying to get a segment closest point on a surface and display a circle (or sphere in this case) at that position. I actually get the correct position but I can't get a uniform sphere based on ...
0
votes
0answers
45 views

How does on the fly LOD work?

In the Unreal Engine 5 tech demo, they mention, that there is no need to manually generate LOD levels for each model, because the on the fly LOD system will generate polygons from the original mesh, ...
2
votes
1answer
32 views

Interpreting Image Processing Math Equation

I am reading "Image Processing and Analysis" by Chan and Shen, c 2005 SIAM. They introduce some notation I'm not 100% sure how to interpret: $$ u_0(x)=u(x)+n(x), x=(x_1,x_2) \in \Omega $$ They ...
1
vote
1answer
64 views

Using Bresenham's circle algorithm (or another alternative algorithm) to draw an arc

I'm trying to create some graphic functions for a ZX Spectrum (Z80) machine in assembler. I already have the basics except for the arc. I need a fast algorithm to draw an arc, ideally one that uses ...
0
votes
1answer
40 views

How are digital painting canvas rendered?

Digital painting and raster graphics software like Krita and Photoshop have a canvas where you can paint with brushes. From a programming perspective, how is this canvas rendered? Can it be included ...
1
vote
1answer
56 views

OpenGL task/mesh shader extension NV_mesh_shader not behaving as I expected

I am trying to get up to speed with the NV_mesh_shader extension from NVidia (on my RTX2080). Samples are rare, so I tried to come up with my own small sample. I am rendering a sphere (20 triangles) ...
0
votes
1answer
45 views

Force int array to compact memory

I have following structure which i use as an uniform buffer object. ...
0
votes
1answer
37 views

How to use PCA to reconstruct 3D Mesh?

Given a set of human body mesh {S_i}, for each S_i, the points are N*3, we can do PCA on that. We can use PCA to reduce the dimension of {S_i}, for example to k dimension. Let the main direction of ...
1
vote
1answer
78 views

Has anyone found an analytic solution to the product of spherical gaussians from Xu et al?

In section 4.2 of this paper: http://cseweb.ucsd.edu/~ravir/274/15/papers/a209-xu.pdf Xu et al approximate the product of 2 anisotropic Gaussian distributions. I want to know if someone has found not ...
0
votes
1answer
46 views

Converting Vertex and Index buffers to a File Format

I have many sets of vertex and index buffers that I’d like to render on to the screen. Ideally each model in different locations with-in world space. I’m actually doing a statistical study on spatial ...
1
vote
0answers
48 views

Why does processing dense geometry consume less power than simple geometry?

In The Road to PS5, Mark Cerny states: It's counter-intuitive, but processing dense geometry typically consumes less power than processing simple geometry. Why is this the case?
2
votes
1answer
48 views

Do you have to group and optimize your draw and shader calls in Vulkan?

This is in reference and contrast to the discipline (or more or less requirement) of opengl to group draws that use the same materials together, to minimize making many draw calls or many switch ...
0
votes
0answers
24 views

How to measure the reflectance of a material without using a Spectralon

I am trying to measure the reflectance% of a surface (it is made of Teflon and is very white). I am using a line spectrometer. I believe the piece can replace an expensive Spectralon for some ...
2
votes
1answer
35 views

Calculate the position and rotation needed to have a camera look at a certain region

I have a 2D region defined by 4 points in 3D space. I want to position my camera so that it looks at the region, with a settable variable determining which side it looks at, where looks at means that ...
2
votes
0answers
29 views

Per-object screen space uv issue

I am currently trying to sample a texture in screen space. This works well : ...
3
votes
1answer
63 views

How to keep an object constant in screen space?

If you open the modern Blender UI and select for example scaling, and then you use the scroll wheel to "zoom" (move the camera along the radial axis). You will notice that the size of the 3D widget ...
0
votes
1answer
36 views

glutSolid* source code

I am trying to build a dedocohedron in OpenGL, and I know that there is a built-in function in GLUT for the purpose. I was wondering if there is a way to either see the sourcecode for those functions, ...

15 30 50 per page
1
2 3 4 5
58