Thin Border on Image Tiles

[rdfowkes]

I'm generating multiple tile sets with MapTiler and the final png
images have a narrow border around the outside extents of the tile
set. This is causing neighboring tilesets to display a line between
them. Any thoughts how I can get rid of this border?

[Klokan Petr Pridal]

Hi,

The thin black border is caused by scaling down the base tiles into
the overview tiles.
The black color is coming from not filled areas, which are by default
0 - such black pixels are affecting the pixels on the border of
transparency, unless NODATA is set in GDAL for rescaling.

To avoid the black borders you should use the 'antialias' resampling
for the overview tile generation.

This is not yet supported in MapTiler GUI, but you can use it from
GDAL2Tiles command line utility with the parameter -r 'antialias'.
This functionality depends on PIL (Python Imaging Library) which you
need to install in your system.

I am going to provide the 'antialias' scaling in the future MapTiler
version, but I can't tell any schedule for releasing it now.

Best regards

Klokan Petr Pridal

[Roger Fowkes]

Thank you for the follow-up. I am trying a second approach with MapTiler
and am using a very large .ECW file... almost 60gig. Do you know what I
might expect with an image this size? It has been at work for a couple of
hours, but no progress is shown.

Roger Fowkes
MiraLinx, LLC
(480) 208-1050
(480) 233-2075 Mobile
ro...@miralinx.com

[Roger Fowkes]

Attempting to use gdal2tiles on a large .ecw file

gdal2tiles -v -s ESPG:2276 -z 10 [file] [dest]

After running the above command line, I get a popup window "Python.exe has
stopped working" and the following error on the command line...

ERROR 6: No translation an empty SRS to PROJ.4 format is known

Any ideas why I'm getting this error?

Roger Fowkes
MiraLinx, LLC
(480) 208-1050
(480) 233-2075 Mobile
ro...@miralinx.com

-----Original Message-----
From: mapt...@googlegroups.com [mailto:mapt...@googlegroups.com] On Behalf
Of Klokan Petr Pridal
Sent: Wednesday, June 17, 2009 1:41 AM
To: MapTiler User Group
Subject: [maptiler] Re: Thin Border on Image Tiles

[klo...@gmail.com]

Hi Roger,

In my opinion there is an problem with ECW driver in the Windows
version of GDAL and huge size of the input files.
I did not yet reproduce it on my hardware, but I have a report from
another user of GDAL2Tiles about the halt of the rendering after some
time in MapTiler for a huge ECW. Is that you case as well?

On my Linux based rendering infrastructure I have never seen it and I
was tiling compressed ECW with size over 2 GB
(uncompressed more then 30 GB) without any problems.
Would it be hard for you to test the rendering workflow under Linux or
another UNIX on your hardware?

We should report this as a bug to GDAL trac, there was a similar kind
of problem (but not the same) a couple of month ago documented here:
http://trac.osgeo.org/gdal/ticket/803

> gdal2tiles -v -s ESPG:2276 -z 10 [file] [dest]
>
> After running the above command line, I get a popup window "Python.exe has
> stopped working" and the following error on the command line...
>
> ERROR 6: No translation an empty SRS to PROJ.4 format is known

This sounds like if the definition of the epsg:2276 was not correctly
loaded from the epsg database of GDAL for some reason.
Can you try to use this instead?

gdal2tiles -v -s http://www.spatialreference.org/ref/epsg/2276/ -z 10
[file] [dest]

Best regards,

Klokan Petr Pridal
--
http://blog.klokan.cz/
http://www.maptiler.org/
http://www.oldmapsonline.org/

[Roger Fowkes]

Klokan,

I'm trying to use the "antialias" feature of the gdal2tiles command line. I
have to install the PIL and NumPY applications in order to use the feature.
PIL will not install without Python 2.5 registered within Windows. Can you
give any assistance on how to register PIL with Windows?

Roger Fowkes
MiraLinx, LLC
(480) 208-1050
(480) 233-2075 Mobile
ro...@miralinx.com

-----Original Message-----
From: mapt...@googlegroups.com [mailto:mapt...@googlegroups.com] On Behalf
Of klo...@gmail.com
Sent: Wednesday, June 24, 2009 1:28 AM
To: mapt...@googlegroups.com
Subject: [maptiler] Re: Thin Border on Image Tiles