TILEINDEX and overviews (gdaladdo) ?

Thu Sep 29 07:38:50 EDT 2005

Hi Manfred,
I think it's normal, and that viewing a footprint of 20km*20km will need to access around 400 files, then mosaic the overviews, which cannot be lightning speed.
I experienced the same slowdown when trying to open more than a dozen of file with overviews.

My solution is to create already mosaicked overviews, which I add as new layers into my mapfile. A minscale/maxscale helps choosing the correct layer.
Tell me if you need more details (maybe that approach is not what you're lokkin for)

cheers,
Frederic Claudel

>>> Manfred Zerndl <manfred.zerndl at BVV.BAYERN.DE> 29/09/2005 12:42 >>>
Does mapserver not take advantage of overviews calculated with 
"gdaladdo" when
the files are accessed with TILEINDEX?

I have 77300 TIFF-Files. Each of them has 2500x2500 Pixels and each is 
equivalent to one square kilometer
(Ground-resolution is 0.4 meters per pixel (1000 meters / 2500 pixels)).

(by the way, creating a Tile-Index with gdaltindex failed, becuase of 
the amount of comand-line parameters.
So I generated a tileindex-Shapefile for my own, calculated each 
bondingbox and used the tools "shpadd" and "dbfadd".)

For each of the 77300 TIFF-Files I generate overviews with the tool 
"gdaladdo"
(for example: gdaladdo -r average file77300.tif 2 4 8 16 32 64 128)

Then I add the layer in the mapfile as following:

LAYER
  NAME "DOP"
  TILEINDEX "dop/dop.shp"
  TILEITEM "LOCATION"
  TYPE RASTER
  STATUS ON
END

When I try with mapserver to view 200 meters with an image size of 500 
Pixel,
the response is reasonably fast, because mapserver do not have to scale 
the image
(the ground-resolution is 0.4 m/px).
But when I try to view 10 km or 20 km (kilometers) with an imagesize of 
500 pixel,
mapserver take a very long time to answer (up to 1 Minutes).

Does mapserver not take advantage of the precalculated overviews in the 
tiff-files generated with "gdaladdo"
when the files are accessed with TILEINDEX?

I have compiled mapserver on linux with  --with-gdal and --without-tiff !!

$ mapserv -v
MapServer version 4.6.0 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP 
OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=FREETYPE SUPPORTS=WMS_SERVER 
SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT 
SUPPORTS=WCS_SERVER SUPPORTS=FASTCGI SUPPORTS=GEOS INPUT=EPPL7 
INPUT=POSTGIS INPUT=OGR INPUT=GDAL INPUT=SHAPEFILE

Regards, Manfred

----- <start of additional infos> ---

Each of my TIFF-Files looks like this:

$ gdalinfo file77300.tif
Driver: GTiff/GeoTIFF
Size is 2500, 2500
Coordinate System is `'
Origin = (4467999.800000,5321000.200000)
Pixel Size = (0.40000000,-0.40000000)
Metadata:
  TIFFTAG_XRESOLUTION=125
  TIFFTAG_YRESOLUTION=125
  TIFFTAG_RESOLUTIONUNIT=3 (pixels/cm)
Corner Coordinates:
Upper Left  ( 4467999.800, 5321000.200)
Lower Left  ( 4467999.800, 5320000.200)
Upper Right ( 4468999.800, 5321000.200)
Lower Right ( 4468999.800, 5320000.200)
Center      ( 4468499.800, 5320500.200)
Band 1 Block=2500x1 Type=Byte, ColorInterp=Red
  Overviews: 1250x1250, 625x625, 313x313, 157x157, 79x79, 40x40, 20x20
Band 2 Block=2500x1 Type=Byte, ColorInterp=Green
  Overviews: 1250x1250, 625x625, 313x313, 157x157, 79x79, 40x40, 20x20
Band 3 Block=2500x1 Type=Byte, ColorInterp=Blue
  Overviews: 1250x1250, 625x625, 313x313, 157x157, 79x79, 40x40, 20x20

The tool "tiffinfo" generates this:
TIFF Directory at offset 0x11e685a
  Subfile Type: (0 = 0x0)
  Image Width: 2500 Image Length: 2500
  Resolution: 125, 125 pixels/cm
  Bits/Sample: 8
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Orientation: row 0 top, col 0 lhs
  Samples/Pixel: 3
  Rows/Strip: 1
  Planar Configuration: single image plane
TIFF Directory at offset 0x11e6920
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 1250 Image Length: 1250
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes
TIFF Directory at offset 0x11e732e
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 625 Image Length: 625
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes
TIFF Directory at offset 0x11e7634
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 313 Image Length: 313
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes
TIFF Directory at offset 0x11e77ba
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 157 Image Length: 157
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes
TIFF Directory at offset 0x11e78c8
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 79 Image Length: 79
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes
TIFF Directory at offset 0x11e798e
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 40 Image Length: 40
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes
TIFF Directory at offset 0x11e7a54
  Subfile Type: reduced-resolution image (1 = 0x1)
  Image Width: 20 Image Length: 20
  Tile Width: 128 Tile Length: 128
  Bits/Sample: 8
  Sample Format: unsigned integer
  Compression Scheme: None
  Photometric Interpretation: RGB color
  Samples/Pixel: 3
  Planar Configuration: separate image planes

----- <end of additional infos> -----

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