I forgot one obvious test. Is the problem related to the total number of objects in a project or the maximum number of objects in any single population

The example above successfully rendered a population 3000 x 3500 (10.5km

^{2}) with a spacing of 10. I ran another test on another computer with only 1Gb RAM with 9 populations of 2000 x 2000 with the same spacing. That's 18km

^{2}, so it would appear that the problem is related to the number of objects in a population rather than the total number of objects in all of the populations.

This should provide an extra clue into tracking down the problem.

**Suggested workaround**Giving a small safety margin I'll try calculating the maximum size of a particular population using:

(length x width)/spacing

^{2} < 100,000

... and then just tiling populations to make up any shortfall in coverage.

Fingers crossed

**Update:** The grass spacing in my project is 0.5. Using square tiles to simplify the above formula to calculate the maximum width of a population:

Max width = sqrt (spacing

^{2} x 100,000) = 158m in this case.

I set up 4 populations with a width of 150m and the sequence doesn't crash

. I've set up an excel spreadsheet to give me a maximum width and to generate coordinates for tiled populations to replace my large populations. Now to replace all of my populations and try again.