gis - How to filter spatial data -

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I have a database of map points, and I want to limit the display to show a maximum of ~ 50 points at a time . When a user zooms in, more points can be displayed.

Currently, I'm just taking a random sample of the results set. It is not very good, because there can be empty areas, when suddenly zoom in these show a point

My next idea was that I could make a 10x5 grid, and would repeat the results if the grid A place was empty, so I show a point. This solves the previous problem, but the user does not even understand where the focused areas are. Also, it is quite slow if the user decides to zoom out the whole world.

Right now, I am not using any spatial algorithm to sort the data. My plan is to do the right thing before, and then get it fast. Reading a bit in RT, KD-tree and tractor-trees, I did not find anything that helps me to select the 'smart' subset of the sample . It seems that some type of width should be done first, which should solve this problem very easily.

How to break its basic idea about the expansion of a bit into a grid, then that area Use the density analysis to make different size points based on the number of features. In this way, a user has more information about the feature density by looking at larger (or smaller) points.

To make it fast, it is possible that you can set thresholds for each grid. If the count comes on a certain amount, then go to the next grid. In this way, you can "max" point and speed things by ignoring the points above artificially set thresholds (which you can determine based on an empirical analysis of your data).


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