Tiling and overview for a large raster data-set
simboss1 at GMAIL.COM
Thu Jun 16 18:47:34 EDT 2005
I am quite new to Minnesota MapServer, and I need to solve this problem
I have a large dataset of 20.000 tiff images with their world files covering
the urban area of Tampa (FL). I eould like to server them using the WMS
interface of MapServer.
As you can guess the are covered is quie small and the resolution of each
image is pretty big. What I am trying to avoid is having too load to many
tiles as the user zoom out in order to reduce the memory and processor
consumption. The right level of zoom is like 10 tiles at a time, as you zoom
out the image loose its importance and could even stop to be rendered!
I read all the documentation avalaible and many messages on this ml and I
came up with this solution.
1>create an index using gdaltindex for the overall data set.
2>create various level of overview for each image in the dataset using
3>serve the images as a whole layer twaking the MINSCALE and MAXSCALE factor
in the WEB category of the map file.
I managed to do the first two steps (it is not so difficult I know...), I
am having troubles with the third step.
How should I set those two parameters in order to take advantage of the
overviews that I created for each tile?
How can I prevent the user from zooming out too much?
What I basically need, is a way to prevent the server from loading too many
tiles (even if they have overviews) but I want to let the user being able to
zoom in down to the single tile level and maybe a bit more in order to see
the beauty of the high resolution imagery I am serving.
How can I interact with the Scale parameter to tweak this zooming issue?
Am I missing some steps?
Please let me know, it is really important to me right now.
PS I know that maybe someon already answered this questions, if so hust
give me some pointers and excuse me if I posted this question again!
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