Questions tagged [projections]
Questions about the conversions of a 3D model to a 2D model.
142 questions
4 votes
2 answers
1k views
Why is my orthographic projection funky looking?
vertices are all defined in NDC by default, so i used an identity matrix as a base, and only used the translation part to define the visible region. the orthographic projection values: l r b t n f -1, ...
- 99
0 votes
0 answers
49 views
How to select multiple objects in a 3D scene with perspective?
I would like to select multiple object from a rectangle drawn with the mouse. But once unprojected, the rectangle become a trapeze. These objects are on an inclined plane facing the camera. The ...
- 101
0 votes
0 answers
90 views
Projection matrix to Intrinsic parameters
I want to convert a projection matrix in the following form: $$ {\bf P} := \begin{pmatrix} \frac{f}{a \tan\left(\frac{f}{2}\right)} & 0 & 0 & 0 \\ 0 & \frac{f}{\tan\...
- 1
0 votes
1 answer
107 views
Transforming UVs from rectangular to azimuthal spherical projection
I'm trying to figure out a general way to project a rectangular texture into a spherical one centered on the azimuth (UN flag style). As a reference, I have been able to achieve this effect exactly ...
0 votes
1 answer
63 views
Why does one matrix correctly project points to the plane, but another one doesn't?
I have a scene with a floating cube and a plane y=0. I want to create a simple planar shadow of the cube on the plane. To do this, I just have to project the vertices of the cube to the plane. I can ...
- 101
0 votes
1 answer
86 views
Ray direction in VR (Vision Pro)
I am trying to calculate the ray direction for each pixel in a post processing shader on the Vision Pro for raymarching. I am using the inverse of the projection matrix created from the tangents ...
- 101
0 votes
0 answers
68 views
Name of non-standard perspective projection where parallel lines do not meet at a single vanishing point
I have made a non-standard perspective projection for a rectangular room (see left figure), in which for stylistic reasons, I chose to make the perspective "width" of the walls equal ...
- 1
1 vote
1 answer
142 views
In perspective projection matrices, why isn't $z_\text{eye}$ mapped linearly to NDC?
As far as my understanding goes, in projection matrices $x_\text{eye}$ and $y_\text{eye}$ are mapped linearly to NDC by first using proportions to find $x_n = \frac{n\cdot x_e}{-z_e}$ and $y_n = \frac{...