32
votes
Accepted
Faster way to compute the distance from a point to a surface in 3D
Well, you can use the undocumented RegionDistance which does exactly this as follows: (This answer, as written, only works for V9 as noted by Oska, for V10 see ...
- 32.5k
17
votes
Accepted
How to mesh a region using adaptive cubic elements
I discarded my previous approach to generate cubes, then fuse them together, since it seems to do a lot of wasted work. Instead, I propose here my version of a cartesian mesher.
The approach is ...
- 58.4k
14
votes
Alternative to the `DiscretizeRegion`?
I'd say that if the problem is to style the result of DiscretizeRegion, then you don't have a problem :-)
You can use MeshCellStyle to indicate the styles to apply ...
- 58.4k
13
votes
Accepted
Exact symbolic area of an intersection of two polygons with parameters
Having Area generate conditions is informative:
...
- 58.4k
11
votes
Accepted
RegionNearest and neighborhoods
If you don't mind using undocumented stuff, you can access lots of useful properties by converting the BoundaryMeshRegion to a ...
- 83.3k
11
votes
Accepted
How do I get a MeshRegion from an obj file, or from Geometry3D
Well, you have to first convert it to a MeshRegion. Let's take the space shuttle for example:
...
- 32.5k
11
votes
Accepted
11
votes
Accepted
User-defined DistanceFunction for RegionNearest
I don't think there's any way to give RegionNearest a user defined DistanceFunction. I don't see an ...
- 32.5k
10
votes
How to mesh a region using adaptive cubic elements
My take on the problem. We start with the largest cuboids and break down the border cuboids into four smaller cuboids. The function can be nested as many time as needed.
...
- 9,138
9
votes
Accepted
Probable Bug in ConvexHullMesh
This is at least one bug, possibly more. Let me explain:
If we go one step further and use
...
- 35.6k
9
votes
Accepted
Getting cell edges from a picture
Here is an approach based on WatershedComponents and MorphologicalGraph. Some of the steps feel a bit over-complicated, so feel ...
- 23.4k
8
votes
How to plot and find the volume of a solid enclosed by surfaces?
There are a number of ways to do this. Sometimes use of Reduce simplifies the constraints but as Dr Hintze's comment shows Mathematica handles boolean statements ...
- 55k
6
votes
Cutting a section from a sphere by planes
ClipPlanes does exactly what you need:
You can use ClipPlanes in two different ways:
(1) As an option to clip all the 3D ...
- 349k
6
votes
Accepted
Construct a section (or slice) through 3D Regions
Note that RegionIntersection[rr, ip] should give you what you want here but doesn't.
Since we have an axes aligned plane, we can workaround this by exploiting the ...
- 32.7k
6
votes
Accepted
How do I verify a vector identity using Mathematica?
You can use FrenetSerretSystem:
FrenetSerretSystem[{x[s], y[s], z[s]}, s][[-1, -1]] //TeXForm
$\left\{\frac{y'(s) z''(s)-y''...
- 123k
6
votes
Finding shadow area of a 3D object
Here is another approach where you convert a region to a RegionImage. Then you can use ImageRotate to rotate about a vector and <...
- 15.9k
5
votes
Accepted
Possible Bug in DiscretizeRegion with Option MaxCellMeasure
Edit: Wolfram Technical Support has confirmed this as a bug
The only workaround I know is to turn the MeshRegion into a ...
- 32.5k
5
votes
Package for symbolic computation of christoffel symbols and parallel transports in Riemannian geometry, given the metric
The most powerful tensor package suit for MMA (and arguably for any CAS) is xAct. It uses the full machinery of diff geometry (fiber bundles, connections, forms, ect) and a powerful canonicalization ...
- 5,200
5
votes
Accepted
5
votes
Find smallest distance from a point to a Bézier curve
Simply using BezierFunction is not enough. The BezierFunction will not match the BezierCurve ...
- 20.4k
5
votes
Accepted
Minimize relating a geometric test
Not a solution based on Minimize but there are built-in functions to do this.
...
- 15k
4
votes
Is there any way to improve the result of DiscretizeRegion on this 3D ImplicitRegion?
This is a tangential answer to your question, but perhaps it may be of interest nonetheless, in the spirit of providing an alternative approach.
In the case of a cubic region you may be interested ...
- 58.4k
4
votes
Accepted
Simplify behavior: assumption as Interval versus assumption as bounds
Element treats Intervals as geometric regions, and members of those geometric regions are vectors, even when they are of single ...
- 14.6k
4
votes
Accepted
How can one compute a 3D Periodic Delaunay Triangulation using DelaunayMesh?
The main idea is to find the gap position dimension by dimension. Take the first dimension for example, to accomplish that, we first project the hold points set to x axis, and do some very basic but ...
- 26k
4
votes
RegionDifference not working properly for a region from a printable STL file
I have described integrating Mathematica and the open source 3D modeling tool, Blender 2.79b, in previous answers here and here.
Your geometry does have some small features and concavity that can ...
- 15.9k
4
votes
RegionUnion for 3D Regions
Note that this is only an issue with the display -- the region itself is still correct. We can see this by sampling a bunch of random points:
...
- 32.7k
4
votes
Accepted
Periodic boundaries for a 3D walk in a Bravais lattice?
LatticeData makes use of the abstract Mathematica Entity Lattice. This reflects the physical ...
- 3,624
4
votes
Finding shadow area of a 3D object
Your question is fundamentally not about a 3D object, incidentally.
Binarize the image (called image), then find the number of black pixels, and divide by the ...
- 35.8k
4
votes
Given three points in space, find center of circle
Given 3 point, search the center of the circle through these points.
The center of the circle must lay in the same plane as p1,p2,p3, therefore we can write:
...
- 24.3k
3
votes
How do I verify a vector identity using Mathematica?
Since N is a built-in symbol, we will use n instead of N. The required formulas are
...
- 33.8k
Only top scored, non community-wiki answers of a minimum length are eligible