[Xastir] what format to export MrSID for xastir use?

[Tom Russo]

On Fri, Jan 28, 2005 at 07:59:38AM -0800, we recorded a bogon-computron collision of the <archer at eskimo.com> flavor, containing:
> On Fri, 28 Jan 2005, Derrick J Brashear wrote:
> 
> > >> which type would that be? the drgs and the doqs seem to be different.
> > >
> > > USGS DRG format.  That's the format that all of the speedups were
> > > tuned for.
> >
> > well, need is relative. the doqs do work.
> 
> No argument there!
> 
> That said, either method should work.  Perhaps go with DOQQ-type
> format first, and if you really need speedups later, re-convert.

The UNM RGIS project has all of the DOQQs for my state available in
MrSID.  Just last week I started downloading them and converting to
GeoTIFF with the Windows mrsiddecode utility from Lizardtech.  I
didn't specify any conversion parameters, but it seems as if the
result was geotiff files in strips and not tiles:

 > tiffinfo 34106H31.tif
  Image Width: 6452 Image Length: 7618
  Bits/Sample: 8
  Compression Scheme: None
  Photometric Interpretation: min-is-black
  Samples/Pixel: 1
  Rows/Strip: 1
  Planar Configuration: single image plane

 > gdalinfo 34106H31.tif
PROJCS["NAD83 / UTM zone 13N",
    GEOGCS["NAD83",
        DATUM["North_American_Datum_1983",
            SPHEROID["GRS 1980",6378137,298.2572221010002,
                AUTHORITY["EPSG","7019"]],
            AUTHORITY["EPSG","6269"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4269"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",-105],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","26913"]]
Origin = (374076.000000,3874214.000000)
Pixel Size = (1.00000000,-1.00000000)
Corner Coordinates:
Upper Left  (  374076.000, 3874214.000) (106d22'47.87"W, 35d 0'9.77"N)
Lower Left  (  374076.000, 3866596.000) (106d22'43.72"W, 34d56'2.54"N)
Upper Right (  380528.000, 3874214.000) (106d18'33.39"W, 35d 0'12.59"N)
Lower Right (  380528.000, 3866596.000) (106d18'29.46"W, 34d56'5.35"N)
Center      (  377302.000, 3870405.000) (106d20'38.61"W, 34d58'7.58"N)
Band 1 Block=6452x1 Type=Byte, ColorInterp=Gray
  Offset: -0.122468,   Scale:-0.122468


They work fine, and seem to benefit from the DRG speedups.  I do see,
though, that the file size balloons from 2.7Mb in MrSID format to
almost 50MB in GeoTIFF --- even if I enable packbits compression.
Pity, that.

-- 
Tom Russo    KM5VY     SAR502  DM64ux         http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 
 "When life gives you lemons, find someone with a paper cut."