[mapserver-users] preparing orthos for Mapserver?

[Even Rouault]

Le dimanche 13 octobre 2013 20:31:26, Worth Lutz a écrit :
> This seems to be working but I'm getting this message on one set of tiles:
> 
> ERROR 1: Maximum number of characters allowed reached.
> Input file size is 10000, 10000
> 0...10...20...30...40...50...60...70...80...90...100 - done.
> 
> I get an output file which I can then add overviews.  Any idea what the
> ERROR means? I can find no explanation.

This error comes from a routine in GDAL that read files line per line. It is 
emitted when the line is too long. It must be some companion file of your input 
dataset that causes this. What is the list of files reported by gdalinfo ?

> 
> Thanks,
> Worth
> 
> -----Original Message-----
> From: mapserver-users-bounces at lists.osgeo.org
> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Rahkonen
> Jukka Sent: Saturday, October 05, 2013 6:31 AM
> To: mapserver-users at lists.osgeo.org
> Subject: Re: [mapserver-users] preparing orthos for Mapserver?
> 
> Hi,
> 
> Have also definitely a try with JPEG compressed tiffs. You can save 90% of
> the disk space with nominal effect on speed and quality, but that depends
> on your hardware and imagery.  It is still worth testing. The command to
> use is
> 
> gdal_translate -of GTiff -co tiled=yes -co compress=JPEG -co
> photometric=YCBCR
> 
> For overviews use
> gdaladdo -r average -ro --config COMPRESS_OVERVIEW JPEG --config
> PHOTOMETRIC_OVERVIEW YCBCR
> 
> With or without -ro is a matter of taste. By using internal overviews you
> will save a bit more space because external overviews have some ballast but
> if you want to archive images sometimes you can discard the external
> overviews and save some disk space by that time.
> 
> Tiffs are not as hopeless than plain JPEGs of PNGs and images do not need
> to be read totally into memory.
> Untiled tiffs are usually written in stripes so for reading a box from an
> arbitrary place inside the image it is enough to read all the scan lines
> which intersect that box. It is still more data than what is needed with
> tiled images.
> 
> There are also clever tiff readers which can read fast, let's say, every
> 10th row and column from uncompressed tiff and create an subsampled,
> nearest neighbour subsample in-the-fly. I have used one such in the 90's
> and Intel 386 computers could handle pretty well uncompressed tiffs of
> size
> 10000x10000 pizels without overviews. I think that GDAL can't do that kind
> of selecting and this is more nice-to-know stuff from the stone age. What
> to remember is that tiles and overviews are essential for GDAL and
> Mapserver.
> 
> -Jukka Rahkonen-
> ________________________________________
> 
> Stephen Woodbridge wrote:
> > On 10/4/2013 3:45 PM, Worth Lutz wrote:
> >> I have a question on preparing a set of orthophoto tiff files for use
> >> with MapServer.
> >> 
> >> The orthophotos are 10,000 x 10,000 pixels with 6 in. resolution.
> >> 
> >> Currently I have a tile index pointing to these files.
> >> 
> >> I'm wondering about internal tiling and overlays. Should I process these
> >> tiles with gdal to internally tile each one and add internal overlays.
> >> 
> >> I'm thinking that the overlays would be more useful that the internal
> >> tiling based upon the size of the current tiles.
> > 
> > Yes, you should do both of these. The internal tiling is very important
> > when you access a very small part of the image so you do not have to
> > pull the whole image into memory just to access a small part of it.
> > 
> > The overlays are import when you are zooming out so you do not have to
> > resample on the fly.
> > 
> > -Steve W
> 
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