[mapserver-users] How to Optimize Particular Raster Lookup

[Blake Crosby]

Hello! Wondering if a few of you can provide some insight here:

Problem: Given a linestring, return the elevation data along that
linestring from CDED data (ASCII DEM).

I'm using Mapserver 5.4.2

I'm using PHP Mapscript and queryByPoint to get values from my DEMs.
However, the performance seems really slow. Essentially here is how I
have things set up:

Fetch Linestring from postgis, and select N points from the string every
Y distance (ie, get the points every 1 km).

Loop through each point and do a queryByPoint() to get the value from
Mapserver.

I've tried using a tilecache, yo no avail. It still takes over 60
seconds to query approx 200 points.

I would like to use the 50k CDED dems, however the performance is even
worse. So i'm using the 250k ones, approx 4,280 files.

Any tips on improving performance?

Blake