Thanks, you helped me a lot
In my example, I have printed an area of aproximately 1km wide on an A4
Landscape that is 29,7cm wide, so 1inch is about 85.5m. So that should be
the reason? :-)
regards, dejan
Rahkonen Jukka [EMAIL PROTECTED] wrote on 31.07.2008 11:00:15:
Hi,
What are the dimensions of the image you have captured in real world
utits? Your original aerial images have half a metre pixel size.
It mean that at 300 dpi one original image pixel corresponds with
one pixel at paper if square inch on your printout is presenting
exactly 150 by 150 meters in nature. That is the maximum quality
you can achieve. If square inch on paper equals to 75 by 75 meters
the maximum quolity is achieved already at 150 dpi. Multiplicating
original image pixels for printing cannot improve the quality. But
if you have zoomed out so far that creating output image means
downsampling the original imagery you should see the differense.
So, if your 2150x low resolution image is covering a
considerably larger area than 1075x555 meters in real world it
should look better when downloaded at 300 dpi with 4300x pixels.
-Jukka Rahkonen-
Lähettäjä: [EMAIL PROTECTED] [mailto:
[EMAIL PROTECTED] Puolesta [EMAIL PROTECTED]
Lähetetty: 31. heinäkuuta 2008 9:32
Vastaanottaja: mapserver-users@lists.osgeo.org
Aihe: Re: [mapserver-users] Output image resolution - explanation needed
Thanks Steve
I still (unfortunatelly) don't understand why I am getting the same
quality image on the paper with the first and second print (the
second image has twice more pixels). Is it because of the input
image itself? To be specific - the raster input is aerial image that
gdalinfor reports as:
Driver: GTiff/GeoTIFF
Files: 5C14-05-DOF.tif
Size is 4500, 6000
Coordinate System is `'
Origin = (5419000.15465885310,4964998.79465280470)
Pixel Size = (0.499829146050620,-0.499829146050620)
Corner Coordinates:
Upper Left ( 5419000.155, 4964998.795)
Lower Left ( 5419000.155, 4961999.820)
Upper Right ( 5421249.386, 4964998.795)
Lower Right ( 5421249.386, 4961999.820)
Center ( 5420124.770, 4963499.307)
Band 1 Block=256x256 Type=Byte, ColorInterp=Red
Overviews: 2250x3000, 1125x1500, 563x750, 282x375
Band 2 Block=256x256 Type=Byte, ColorInterp=Green
Overviews: 2250x3000, 1125x1500, 563x750, 282x375
Band 3 Block=256x256 Type=Byte, ColorInterp=Blue
Overviews: 2250x3000, 1125x1500, 563x750, 282x375
regards, dejan
Steve Lime [EMAIL PROTECTED] wrote on 30.07.2008 21:13:55:
Resolution in MapServer-speak is referring to the resolution of the
output device a map
will be displayed on. The value is used for scale computations and
nothing else. It does not
affect the size (in pixels) of MapServer. Scale values do impact the
size at which features
and text are rendered IF scaling (via SYMBOLSCALE) is turned on.
Higher quality output is
usually a matter of having more pixels to print, however you usually
want larger features
too which is where the resolution parameter combined with scaling can
help.
Steve
On 7/30/2008 at 2:21 AM, in message
[EMAIL PROTECTED],
[EMAIL PROTECTED] wrote:
Hi,
I am trying to download a high resolution image and print it on
a paper. I
am using p.mapper and its download function that enables downloading
the
map image on different resolutions.
I have turned on my raster layer (ortophoto image). I have
zoomed in to an
area of interest. I have downloaded the map twice - with a
resolution of
150 and 300. The image is shown i a new page/tab (firefox). I right
click
on the image and save it as a png (also tried with a jpeg) file.Now,
the
first file is 2150x pixels, 120 dpi vertical and horizontal
resolution
(right click on a file, properties, summary, what does it mean?),
the
second file is 4300x pixels, 120 dpi vertical and horizontal
resolution. Seems ok. The second image is doubled in pixel size.
Now, when I try to print this image on A4 paper, using 300dpi, the
images
are the same, there is no better quality in second image.
I have just finshed reading the Mapserver thread on Change image
resolution in mapfile. Several limitations are mentioned there -
max.
image size supported by Mapserver, resolution value/tag embedded
in
output format, etc. Can it be related to my problem? Or is it maybe
that
software I am using to print this image doesn't use this extra
pixels?
Or I am just missing some basic stuff I need to know :-(
thanks very much on any explanation
regards, dejan
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