3d – Page 4 – Tarik Billa

interpolate 3D volume with numpy and or scipy

August 2, 2023 by Tarik

In scipy 0.14 or later, there is a new function scipy.interpolate.RegularGridInterpolator which closely resembles interp3. The MATLAB command Vi = interp3(x,y,z,V,xi,yi,zi) would translate to something like: from numpy import array from scipy.interpolate import RegularGridInterpolator as rgi my_interpolating_function = rgi((x,y,z), V) Vi = my_interpolating_function(array([xi,yi,zi]).T) Here is a full example demonstrating both; it will help you understand … Read more

Hashing 2D, 3D and nD vectors

July 26, 2023 by Tarik

There’s a spatial hash function described in Optimized Spatial Hashing for Collision Detection of Deformable Objects. They use the hash function hash(x,y,z) = ( x p1 xor y p2 xor z p3) mod n where p1, p2, p3 are large prime numbers, in our case 73856093, 19349663, 83492791, respectively. The value n is the hash … Read more

3d surface plot with xyz coordinates

July 20, 2023 by Tarik

calculating distance between a point and a rectangular box (nearest point)

July 15, 2023 by Tarik

Here is a single formula that avoids all the case logic. (I happen to be working in JS right now, so here’s a JS implementation). Let rect = {max:{x:_, y:_}, min:{x:_, y:_}} and p={x:_, y:_} function distance(rect, p) { var dx = Math.max(rect.min.x – p.x, 0, p.x – rect.max.x); var dy = Math.max(rect.min.y – p.y, … Read more

How to convert a 3D point into 2D perspective projection?

July 8, 2023 by Tarik

The standard way to represent 2D/3D transformations nowadays is by using homogeneous coordinates. [x,y,w] for 2D, and [x,y,z,w] for 3D. Since you have three axes in 3D as well as translation, that information fits perfectly in a 4×4 transformation matrix. I will use column-major matrix notation in this explanation. All matrices are 4×4 unless noted … Read more

Disable vertical sync for glxgears

June 27, 2023 by Tarik

The vblank_mode environment variable does the trick. You should then get several hundreds FPS on modern hardware. And you are now able to compare the results with others. $> vblank_mode=0 glxgears

3D Scene Renderer for Python [closed]

June 15, 2023 by Tarik

Really depends exactly what you want to accomplish. How complex is your scene? What sort of render quality are you after? Do you need real-time animation, or are rendered stills good enough? First-rate, full game engines (have been used for commercial games) Panda3d http://www.panda3d.org/ PyOgre http://www.ogre3d.org/tikiwiki/PyOgre Pyrr (Irrlicht wrapper) Less popular 3d engines, new or … Read more

Projecting 3D points to 2D plane [closed]

June 15, 2023 by Tarik

If you have your target point P with coordinates r_P = (x,y,z) and a plane with normal n=(nx,ny,nz) you need to define an origin on the plane, as well as two orthogonal directions for x and y. For example if your origin is at r_O = (ox, oy, oz) and your two coordinate axis in … Read more

Three.js Projector and Ray objects

June 10, 2023 by Tarik

I found that I needed to go a bit deeper under the surface to work outside of the scope of the sample code (such as having a canvas that does not fill the screen or having additional effects). I wrote a blog post about it here. This is a shortened version, but should cover pretty … Read more

How to “flatten” or “index” 3D-array in 1D array?

June 4, 2023 by Tarik

Here is a solution in Java that gives you both: from 3D to 1D from 1D to 3D Below is a graphical illustration of the path I chose to traverse the 3D matrix, the cells are numbered in their traversal order: Conversion functions: public int to1D( int x, int y, int z ) { return … Read more