Opened 8 years ago

Last modified 8 years ago

#4211 assigned defect

Layer processing directive RESAMPLING and OFFSITE definition

Reported by: armin Owned by: warmerdam
Priority: normal Milestone:
Component: GDAL Support Version: 6.0
Severity: normal Keywords:
Cc:

Description

The raster layer processing directive like

PROCESSING "RESAMPLE=BILINEAR"

causes some strange effects along the border of DATA-NODATA pixels for the resampling types "bilinear" and "average", but not for "nearest", when the NODATA pixels defined as not displayed/transparent via the map file tag

OFFSITE 0 0 0

This happens only when this border is not along an exact horizontal or vertical line but having an oblique, staircase-shaped borderline (typically the case for warped/rotated images images after reprojection with larger triangular border areas with NODATA).

This happened for GeoTIFF files, with or without overviews. Images were separate tiff images, used via TILEINDEX in MS layers, like

LAYER
  NAME "test_fc"
  TYPE Raster
  TILEINDEX "/home/test/tileindex"
  TILEITEM "location"
  DUMP TRUE
  METADATA
    "ows_title"  "TEST, FALSE COLOR"
  END
  OFFSITE 0 0 0
  PROCESSING "RESAMPLE=BILINEAR"
  PROJECTION
    "init=epsg:3035"
  END
END

The images are correctly pixel-aligned to each other, i.e. having the same grid geometry.

The attached screenshots show the effects.

Software versions used were MS 6.0.1, GDAL 1.9, OS Linux 64bit.

Attachments (3)

wms_resampling-bilinear_02.png (211.0 KB) - added by armin 8 years ago.
wms_resampling-bilinear.png (157.7 KB) - added by armin 8 years ago.
wms_resampling-nearest.png (20.8 KB) - added by armin 8 years ago.

Download all attachments as: .zip

Change History (5)

Changed 8 years ago by armin

Changed 8 years ago by armin

Attachment: wms_resampling-bilinear.png added

Changed 8 years ago by armin

Attachment: wms_resampling-nearest.png added

comment:1 Changed 8 years ago by warmerdam

Status: newassigned

I am going to need a mapfile, mapdata and shp2img command that demonstrates the issue.

I gather you found the problem was *not* related to overview generation in GDAL, right?

comment:2 Changed 8 years ago by armin

yes, this issue seems not to be related to any overviews.

I will prepare 2 or 3 clipped out images and the map file.

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