I have coordinates for 4 vectors defining a quad and another one for it's normal. I am trying to get the rotation of the quad. I get good results for rotation on X and Y just using the normal, but I got stuck getting the Z, since I've used just 1 vector. Here's my basic test using Processing and toxiclibs(Vec3D and heading methods): im...
I'm learning OpenGL (specifically, using JOGL) and I'm trying to create a right-angled triangular prism. I learned you can create an equilateral prism with glutWire/SolidCylinder and a a low number of slices (3 for a triangle, obviously). So I'm wondering if there's some other way to make a prism, or if there's some way to scale an equ...
I'm working on a 3D tile based game and I'm using AABB collision detection. For every cube that the player is intersecting, I find the axis along which the player is intersecting the cube the least, and push the player out of the cube along that axis. Depending on the order that the cubes are checked in, this can cause problems when sli...
Given n segments of line (into the X axis) with coordinates [li; ri]. You are to choose the minimum number of segments that cover the segment [0;M]. Design a greedy algorithm to solve this problem. Here what I did: sorting them by starting points in increasing order, then I choose the longest one, second longest.... But here is a probl...
Hi, I have taken images of the facade of a building under multiple view points. Then I use bundler to reconstruct the 3D point cloud of the building. Then I use a RANSAC method to find the plane of the facade in the point cloud. This gives me the parameters for the plane and its surface normal. From bundler I also get the camera rot...
In the Communications of the ACM, August 2008 "Puzzled" column, Peter Winkler asked the following question: On the table before us are 10 dots, and in our pocket are 10 $1 coins. Prove the coins can be placed on the table (no two overlapping) in such a way that all dots are covered. Figure 2 shows a valid placement of the c...
Hi, i have two Lidar las files, one is original let's say with X points. And the other is copy of the first las file but with Y points, where Y is less than X. Now, i wanted to compare how the Digital Elevation Models of these two las files vary... I wanted to get information like RMSE, standard deviation, etc... I would appreciate, if a...
Given: Given a set of N points in the 2D plane (x and y coordinates), and a set of N radii corresponding to each point. We will refer to a point's disc as the disc centered at the point with its radius. Problem: Cluster the points. A cluster of points is such that each point EITHER falls within the disc of at least one other point in th...
I'm not sure what mathematical concept this is to support my question. ^^ Let's say we have PointA as the reference. The problem is to find the points around PointA within a given radius (Using coordinates). My approach would be to compute the distance of every point (Pythagorean) and then compare with the given radius. I'm sure that th...
Hi, guys, If I get a line segment which was long enough to cross a given polygon, which could be concave or convex polygon. How did I find the all the intersected light segments which was contained in the polygon? If the target region is not polygon, but a implicit curve function or spline curve, how to do it? Thanks! ...
Hi, I need to know how to determine fast if line intersects simple polygon. It should work in O(log n) time, where n is number of polygon's vertexes. I searched in google, but I didn't find anything useful, maybe I'm blind. ;) Edit: I'm using C++ but I think language isn't a problem, and it isn't homework, just doing some algorithms trai...
Given a starting point (origLat, origLon), ending point (destLat, destlon), and a % of trip completed. How do I calculate the current position (curLat, curLon)? ...
I'm trying to implement Jarvis' algorithm for finding the convex hull of a set of points, but for some reason it doesn't work. This is my implementation: procedure TPointList.ConvexHull(aHull : TPointList); //Return the convex hull of a set of 2D points var vPointOnHull : TPoint2D; vEndpoint : TPoint2D; I : intege...
Is surface always locally connected? I mean, is it true, that it two points belong to this surface, that there exist a continious path (throught other points of a surface)? I feel that it is true but cannot find any confirmation in the internet. ...
Hi All, I have some map files consisting of 'polylines' (each line is just a list of vertices) representing tunnels, and I want to try and find the tunnel 'center line' (shown, roughly, in red below). I've had some success in the past using Delaunay triangulation but I'd like to avoid that method as it does not (in general) allow fo...
I have following task: In the program we should draw lines on a bit mapped display. An array of n pairs of reals (ai,bi) defined the n lines yi = ai*x + bi. The lines were ordered in the x-interval [0, 1] in the sense that yi < yi+1 for all values of i between 0 and n-2 and for all values of x in [0, 1] Less formally, the lines do...
I'd like to be able to extract the geometry for each letter in a TrueType font file. Each letter would have a set of coordinates, assuming each letter is in its own grid. As a picture tells a thousand words - I'd like to get the vertices for letters similar to the image below (courtesy of http://polymaps.org/) Update Thanks to the ...
For a polygon defined as a sequence of (x,y) points, how can I detect whether it is complex or not? A complex polygon has intersections with itself, as shown: Is there a better solution than checking every pair which would have a time complexity of O(N2)? ...
I am looking for a language, or package in an existing language, that is good for specifying and drawing geometric diagrams. For example, I would like to draw a hexagonal grid, with its dual triangular grid superimposed on it. Now, I could sit down, put some elbow grease in to work out the trig by hand and come up with some Postscript o...
I'm starting a new project in .NET which will require some geometry algorithms, such as: checking if a point is inside a polygon bezier curves line intersections, etc. I've found some libraries, however, they are paid/expensive, these include: G# - http://www.ceometric.com/store.html DigitalRune Geometry - http://www.digitalrune.co...