indexing,geospatial,quadtree,r-tree

"restructuring the whole index". No. Restructuring the R-tree is restricted to a single path, not the "whole" index. It works similar to the B-tree, actually. Consider implementing both, and doing some benchmarks yourself, to really know how they perform. Don't only use theory. On uniformly distributed data with a high...

python,algorithm,collision-detection,quadtree

The best way I've found so far is to modify _get_index() to check the entire size of the particle -- if it doesn't entirely fit in a subtree, then it becomes a child of the parent node: def _get_index(self, child): """ Returns the index of the node that the object...

java,algorithm,coordinates,quadtree

The data structure you need is called an R-Tree. Most RTrees permit a "Within" or "Intersection" query, which will return any geographic area containing or overlapping a given region, see, e.g. wikipedia. There is no reason that you cannot build your own R-Tree, its just a variant on a balanced...

This is because you have a double pointer in your code, which you would have to dereference in order to make that line work: printf("%c\n" , p->colour); That is, for example: printf("%c\n" , (*p)->colour); Also, note that you have a global static variable also named p: static struct quadtree *p...

c++,bulkinsert,z-order,quadtree

This is untested code, you should double check if it works. Also, this code is almost certainly not portable, and might even be undefined behavior. It's certainly implementation defined behavior at the very least, but it's probably unspecified... I'd have to more carefully read the rules regarding reinterpret_cast to and...

In addition to the pure collision detection I'd also check, whether the centers of the squares move towards each other or not and only revert their velocity in the first case. For me to provide an example you'd have to provide information about your implementation of the Square class. Edit:...

It sounds like your image is colour (RGB). Try converting the image to grayscale before using the algorithm. I = imread('hyd.tif'); Igray = rgb2gray(I); S = qtdecomp(Igray); Also make sure that your image dimensions are of a power of 2 or else the quadtree decomposition algorithm will not work....

javascript,data-structures,geospatial,region,quadtree

If I understand the wikipedia article the region quadtree holds a bitmap with the full region at each level and the point quadtree holds the convex hull with 4 points.

You would recurse down each node whose bounds overlap with the given rectangle. Here's some pseudo code based on the fields that you mention in your question: int countPointsInRect(Quadtree root, Rectangle r) { // Entire bound of current node outside of given rectangle? if (root.bounds outside r) return 0 //...

It seems to me that your recursive finder is a little over complicated. You are kind of half unrolling the recursion within the function. The following is an example that is maybe a little more 'purely' recursive. It works if I assume that keyExists() works by returning true if there...

The error is pretty clear. Your image must have dimensions that belong to a power of two. As such, you need to resize your image so that it follows this. qtdecomp computes the quadtree decomposition algorithm, and a pre-condition for this function is that it NEEDS to have an image...

Erlang data structures are immutable, so you can't mutate a sub tree without getting a new copy of the original tree. The copy will be sharing as much as possible with the original tree -- which it can only because of said immutability -- so this might sound worse as...