[Mapserver-users] set zoom level to 1:1?

[Ed McNierney]

Twan -

Since your pixels are reported to be 1.5 units in each dimension, you should simply ask MapServer for a map whose spatial EXTENT (i.e. the mapfile EXTENT statement) is 1.5 times the number of pixels in the requested image size.  If you ask for an image that's 400 pixels by 400 pixels, and you ask for geographic extents that are 600 units by 600 units, you'll get exactly one output pixel for each input pixel.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed@topozone.com
(978) 251-4242 

-----Original Message-----
From: Twan Kogels [mailto:twan@twansoft.com]
Sent: Thursday, December 12, 2002 10:01 AM
To: mapserver-users@lists.gis.umn.edu
Subject: [Mapserver-users] set zoom level to 1:1?


Hello list,

Here comes a quick question:
When i open my raster layer in paint shop pro or photoshop, the raster 
(tiff) file is displayed at zoom level 1. You see the streets and parks the 
way it should be.

When i view the raster layer with mapserver the first view is a resized 
raster layer, so it does fit into the boundries of the map extent.

How can i calculate the zoom/scale level which is needed to get the same 
viewing result in mapserver as viewing the raster layer in paint shop pro? 
With other words, how can i zoom into a map so the zoom level is 1:1.

The following informatie may be usefull:
==================
linux:/usr/local/apache/htdocs/haarlem/data/layer1 # 
/usr/local/bin/gdalinfo 1008060.TIF
Driver: GTiff/GeoTIFF
Size is 8000, 5333
Coordinate System is `'
Origin = (95999.250000,488000.750000)
Pixel Size = (1.500000,-1.500000)
Metadata:
   TIFFTAG_SOFTWARE=Handmade Software, Inc. Image Alchemy v1.7.7
Corner Coordinates:
Upper Left  (   95999.250,  488000.750)
Lower Left  (   95999.250,  480001.250)
Upper Right (  107999.250,  488000.750)
Lower Right (  107999.250,  480001.250)
Center      (  101999.250,  484001.000)
Band 1 Block=8000x2 Type=Byte, ColorInterp=Red
   Min=0.000/0, Max=255.000/0
Band 2 Block=8000x2 Type=Byte, ColorInterp=Green
   Min=0.000/0, Max=255.000/0
Band 3 Block=8000x2 Type=Byte, ColorInterp=Blue
   Min=0.000/0, Max=255.000/0
Band 4 Block=8000x2 Type=Byte, ColorInterp=Alpha
   Min=0.000/0, Max=255.000/0
=====================

=====================
linux:/usr/src/packages/SOURCES/mapserver-3.6.3 # ./mapserv -v
MapServer version 3.6.3 OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP SUPPORTS=PROJ 
SUPPORTS=TTF SUPPORTS=WMS_SERVER INPUT=EPPL7 INPUT=JPEG INPUT=POSTGIS 
INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE
=====================

Best regards,
Twan Kogels

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