Here is some code that I use to subdivide envelopes.
/**
* Create a grid of Envelopes for an Envelope with a number of rows and
columns
* @param envelope The Envelope
* @param numberOfRows The number of rows
* @param numberOfColumns The number of columns
* @return An array of Envelopes
*/
public Envelope[] createGrid(Envelope envelope, int numberOfRows, int
numberOfColumns) {
// Extract the origin, width, and height
double minX = envelope.getMinX();
double minY = envelope.getMinY();
double width = envelope.getWidth();
double height = envelope.getHeight();
// Calculate the cell width and height
double cellWidth = width / numberOfColumns;
double cellHeight = height / numberOfRows;
// Calculate the number of cells (Envelopes)
int numberOfCells = numberOfRows * numberOfColumns;
// Create the Envelope array
Envelope[] envs = new Envelope[numberOfCells];
// Fill the Envelope array
int i = 0;
for (int r = 0; r < numberOfRows; r++) {
for (int c = 0; c < numberOfColumns; c++) {
double x = minX + (r * cellWidth);
double y = minY + (c * cellHeight);
envs[i] = new Envelope(x, x + cellWidth, y, y + cellHeight);
i++;
}
}
return envs;
}
Jared Erickson
>>> Sunburned Surveyor <[email protected]> 1/27/2009 4:49 PM >>>
Does anyone know of (or have) code that will take an envelope and
break it up into smaller envelopes of equal size? (I didn't see a
method in the Envelope class that performed this operation.)
Here is my use case:
I've got some shapefiles that are too large to work with in OpenJUMP.
I want to split one of these large shapefiles into a smaller shapefile
that I can work with. To do this I thought I could access the envelope
that covers all features in the Shapefile. I'd split this into a
number of smaller envelopes of equal size. I'll then use code from
deegree/Geotools to iteratively access each feature in the Shapefile
on disk. I'll determine which envelope each feature fits in, and I'll
stick that feature in a new Shapefile.
Thanks for any thoughts. I'll whip up some new code if no one has
existing code to do the trick.
The Sunburned Surveyor
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