Mateusz Loskot :: hacking on, working out, living up

Run WKT Raster, run!

27 Mar 2009 | mloskot

I have a not-so-small GeoTIFF raster dataset. Here is what GDAL has to say about it:

$ gdalinfo japan.tif
Driver: GTiff/GeoTIFF
Files: japan.tif
Size is 14000, 14000
Coordinate System is:
GEOGCS["WGS 84",
    DATUM["WGS_1984",
        SPHEROID["WGS 84",6378137,298.2572235630016,
            AUTHORITY["EPSG","7030"]],
        AUTHORITY["EPSG","6326"]],
    PRIMEM["Greenwich",0],
    UNIT["degree",0.0174532925199433],
    AUTHORITY["EPSG","4326"]]
Origin = (137.386330630776030,38.325757833006122)
Pixel Size = (0.000256020461176,-0.000256020461176)
Metadata:
  AREA_OR_POINT=Area
  TIFFTAG_DOCUMENTNAME=ER Mapper 6.4
  TIFFTAG_IMAGEDESCRIPTION=ER Mapper GeoTiff raster translator V1.0: Band 1 = Red, Band 2 = Green, Band 3 = Blue
  TIFFTAG_SOFTWARE=ER Mapper 6.4
  TIFFTAG_XRESOLUTION=0
  TIFFTAG_YRESOLUTION=0
Image Structure Metadata:
  COMPRESSION=LZW
  INTERLEAVE=PIXEL
Corner Coordinates:
Upper Left  ( 137.3863306,  38.3257578) (137d23'10.79"E, 38d19'32.73"N)
Lower Left  ( 137.3863306,  34.7414714) (137d23'10.79"E, 34d44'29.30"N)
Upper Right ( 140.9706171,  38.3257578) (140d58'14.22"E, 38d19'32.73"N)
Lower Right ( 140.9706171,  34.7414714) (140d58'14.22"E, 34d44'29.30"N)
Center      ( 139.1784739,  36.5336146) (139d10'42.51"E, 36d32'1.01"N)
Band 1 Block=14000x20 Type=Byte, ColorInterp=Red
Band 2 Block=14000x20 Type=Byte, ColorInterp=Green
Band 3 Block=14000x20 Type=Byte, ColorInterp=Blue

I loaded it to PostGIS/WKT Raster table with regular blocking enabled in PostgreSQL 8.3 database running on Ubuntu 8.10 (32-bit) installed as a guest system under VirtualBox:

$ gdal2wktraster.py -r japan.tif -t japan_rb -o japan_rb.sql -k
$ psql -d test -f japan_rb.sql

The loader generated output file japanrb.sql_ of size of 1.1 GB and it makes 700 records (raster tiles or blocks) in the database. The disk usage reported for the raster table is:

sistest=# SELECT relfilenode, relpages FROM pg_class WHERE relname = 'japan_rb';
 relfilenode | relpages 
-------------+----------
       71700 |        5
(1 row)

I run simple test query:

$ psql -d test
test=# SET log_statement_stats TO 1;
SET
test=# SELECT rid FROM japan_rb WHERE RT_Width(rast) != 14000 OR RT_Height(rast) != 20;
 rid
-----
(0 rows)

In the PostgreSQL log I got dumped a bunch of interesting statistics:

2009-03-27 15:23:38 GMT LOG:  QUERY STATISTICS
2009-03-27 15:23:38 GMT DETAIL:  ! system usage stats:
 ! 5.084838 elapsed 2.544159 user 2.468154 system sec
 ! [4.960310 user 5.204325 sys total]
 ! 0/0 [16/28160] filesystem blocks in/out
 ! 0/320190 [0/647479] page faults/reclaims, 0 [0] swaps
 ! 0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
 ! 0/155 [9/327] voluntary/involuntary context switches
 ! buffer usage stats:
 ! Shared blocks:      74192 read,          0 written, buffer hit rate = 51.71%
 ! Local  blocks:          0 read,          0 written, buffer hit rate = 0.00%
 ! Direct blocks:          0 read,          0 written

The virtual machine has assigned 1024 MB of RAM and one CPU Intel Xeon 3.2 GHz.

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