GDAL cannot read multiband ArcInfo Binary Grids

[jjr8]

I created a ArcInfo Binary Grid with 5 bands using ArcGIS 9.3.1. GDAL 1.6.0 cannot read it:

C:\>gdalinfo --version
GDAL 1.6.0, released 2008/12/04

C:\>gdalinfo c:\AIG_Multiband\ccomp2
ERROR 4: `c:\AIG_Multiband\ccomp2' not recognised as a supported file format.

gdalinfo failed - unable to open 'c:\AIG_Multiband\ccomp2'.

ArcCatalog reports the format of c:\AIG_Multiband\ccomp2 is "GRID Stack 7.x". The raster has five bands, all 250 x 250 cells. All of the cells of a given band have the same value, either 0, 1, or 255. (This raster was part of an experiment and does not represent real-world data.)

Frank W indicated that he would like to look at this raster to try to understand the format. It is attached. Thanks for looking.

I have no idea if you want to fix this. It would be helpful to me but I can work around it by using a different format. Please adjust the ticket properties appropriately.

[warmerdam]

I have established that the stack consists of two files:

warmerda@gdal64[99]% ls -l ccomp2
total 20
-rw-r--r-- 1 warmerda warmerda 13208 2009-08-27 18:26 metadata.xml
-rw-r--r-- 1 warmerda warmerda    90 2009-08-27 18:26 stk.adf

The stk.adf file looks like:

warmerda@gdal64[101]% od -c ccomp2/stk.adf
0000000  \0  \0  \0 001   c   c   o   m   p   2   c   1                
0000020      \0  \0  \0  \0 002   c   c   o   m   p   2   c   2        
0000040              \0  \0  \0  \0 003   c   c   o   m   p   2   c   3
0000060                      \0  \0  \0  \0 004   c   c   o   m   p   2
0000100   c   4                      \0  \0  \0  \0 005   c   c   o   m
0000120   p   2   c   5                      \0
0000132

Each of the grids in the stack is parallel to this directory as a normal grid accessable with GDAL.

warmerda@gdal64[104]% du
24      ./ccomp2
28      ./ccomp2c1
28      ./ccomp2c2
28      ./ccomp2c3
28      ./ccomp2c4
28      ./ccomp2c5
160     ./info
376     .

It looks like it would be relatively easy to add a stack driver to pull together the grids, but I have no plans to do this in the short term and it seems that the individual grids are easily accessed already. They could be "stacked" for gdal with gdal_merge.py -separate.

[jjr8]

I have no urgent need for this functionality so, for my part, I am ok with you deferring this to some future point.

Perhaps those who need to access multiband ArcInfo Binary Grids with GDAL could handle it like this:

1. Try to open with the normal GDAL API. If that fails:

2. Check that the raster path is a directory that contains a stk.adf file.

3. Parse the stk.adf file to build a list of single-band AIGs. It looks like the format of that file consists of a list of binary records, where each record is a four-byte integer indicating the band number followed by a fixed-length, 14-character, null-terminated string specifying the single-band AIG. The 13 characters is expected because single-band AIGs are limited to this length. I have read elsewhere that the multiband AIG (the stack) is limited to 9 characters. This is probably so that Arc can append "c" followed by up to three decimal digits.

4. Once you have the names, open them with the normal GDAL open API.

Looks like there is more info here:  http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=About_the_ESRI_grid_format

[jjr8]

Here are additional comments from the gdal-dev list.

-----Original Message-----
From: Peter J Halls
Sent: Friday, August 28, 2009 7:15 AM
To: Andrew Loughhead
Cc: Jason Roberts; gdal-dev@lists.osgeo.org
Subject: Re: [gdal-dev] Does GDAL support ArcInfo Binary Grids with multiple bands?

Andrew is correct.  The ArcGIS grid stack comprises an index to the component 
grids, stackname.stk. The records comprise the grid names.  The grids must be in 
the same location (workspace) and have the same projection / coordinate system 
but do not need to have the same geographic extents (so long as there is an area 
of common overlap) or cell size.  Where the cell size differs, that quoted for 
the stack is the coarsest of the components.

It is quite common to use a stack to collect together raster layers representing 
disparate criteria in order to analyse them together, using geostats, for 
example.  A multi-band stack, such as, for example, might comprise a Landsat TM 
image, is a sort of special case.

Peter

Andrew Loughhead wrote:
> Jason Roberts wrote:
>>
>> Is the GDAL ArcInfo Binary Grid (AIG) driver intended to support AIGs 
>> with multiple bands? I have a 5-band AIG for which the Python gdal 
>> bindings for GDAL 1.6.0 report "`C:\Temp\ccomp2' not recognised as a 
>> supported file format." ArcGIS 9.3.1 reports that the "format" of it 
>> is "GRID Stack 7.x". It was created using standard ArcGIS tools.
>>
> I don't think that its quite right to see a GRID stack as an AIG with 
> multiple bands.
>  From (somewhat long term) memory an ArcInfo Grid Stack is actually a 
> collection of individual grids, rather than a single grid dataset with 
> multiple bands.  Within ArcInfo Workstation stacks can be converted to a 
> few multiband image formats, and multiband images converted to stacks.  
> I *think* that Stacks always have an INFO file, possibly called 
> <stackname>.stk, and I also think that the grids composing a stack had 
> to have identical bounds, and be in the same workspace.  Any particular 
> grid in a workspace could be in zero, one or more stacks.
> 
> Anyway I would expect that GDAL will deal fine with the individual grids 
> in the stack, as individual datasets.  Any GDAL utility, or binding, 
> which can combine individual datasets into a multiband image could 
> therefore convert a stack into an image.  Of course you would need to 
> know which individual grids form the stack.
> hth
> Andrew