EVOLUTION-MANAGER

Edit File: frmt_mem.html

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<title>MEM -- In Memory Raster</title>
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<h1>MEM -- In Memory Raster</h1>

GDAL supports the ability to hold rasters in a temporary in-memory format.
This is primarily useful for temporary datasets in scripts or internal
to applications.  It is not generally of any use to application end-users.<p>

Memory datasets should support for most kinds of auxiliary information
including metadata, coordinate systems, georeferencing, GCPs,
color interpretation, nodata, color tables and all pixel data types.<p>

<h2>Dataset Name Format</h2>

It is possible to open an existing array in memory.  To do so, construct
a dataset name with the following format:

<pre>
  MEM:::option=value[,option=value...]
</pre>

For example:

<pre>
  MEM:::DATAPOINTER=342343408,PIXELS=100,LINES=100,BANDS=3,DATATYPE=Byte,
       PIXELOFFSET=3,LINEOFFSET=300,BANDOFFSET=1
</pre>

<pre>
  MEM:::DATAPOINTER=0x1467BEF0,PIXELS=100,LINES=100,BANDS=3,DATATYPE=Byte,
       PIXELOFFSET=3,LINEOFFSET=300,BANDOFFSET=1
</pre>

<ul>
<li> DATAPOINTER: address of the first pixel of the first band.  The address can be represented as a hexadecimal or decimal value.  Hexadecimal values must be prefixed with '0x'.  Some implementations (notably Windows) doesn't print hexadecimal pointer values with a leading '0x', so the prefix must be added.  You can use CPLPrintPointer to create a string with format suitable for use as a DATAPOINTER.
<li> PIXELS: Width of raster in pixels. (required)
<li> LINES: Height of raster in lines. (required)
<li> BANDS: Number of bands, defaults to 1. (optional)
<li> DATATYPE: Name of the data type, as returned by GDALGetDataTypeName() (eg. Byte, Int16)  Defaults to Byte.  (optional)
<li> PIXELOFFSET: Offset in bytes between the start of one pixel and the next on the same scanline. (optional)
<li> LINEOFFSET: Offset in bytes between the start of one scanline and the next. (optional)
<li> BANDOFFSET: Offset in bytes between the start of one bands data and the next.
</ul>

<h2>Creation Options</h2>

There are no supported creation options.<p>

The MEM format is one of the few that supports the AddBand() method.
The AddBand() method supports DATAPOINTER, PIXELOFFSET and LINEOFFSET
options to reference an existing memory array.<p>

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