Page History

...

The file format was documented by ESRI online. (PDF version) and supports integer (1- to 32- bit) pixel values in signed or unsigned format, in either little- or big endian storage order. The 1- and 4- bit integer pixel formats have not been implemented (yet) as they seem less useful for FEWS, but the rest of the documentation is fully implemented.

Note: It is assumed that your data is using unsigned integers, unless the keyword "pixeltype" is used and its value is"signedint".

BIL files in FEWS

In the Public Interface (PI interface) of FEWS, an implementation of the BIL format is also provided, as documented here.

...

This new implementation is fully compliant with the ESRI technical specifications and can be configured with the new "BILBIPBSQ" identifier, whereas the existing PI implementation of FEWS BIL files uses the identifier "BIL".

Using NoData for missing values

In the header files (*.HDR) which normally come with a BIL / BIP / BSQ file, a NoData field can be used to define the numerical value which has been assigned to pixels for which there is no valid data.  This field is not mentioned in the ESRI documentation but it's usage is very common, as follows:

	NODATA -999

The result if this example is identical to defining <missingValue>-999</missingValue> in the import configuration.

Using NBLOCKS for time series

...

Appending the binary image files (each having the same format and dimensions) to create a time series can be done using (for example) a DOS copy command in binary append mode, as follows:

	copy /b step1.bil+step2.bil+step2step3.bil+step4.bil 4steps.bil

Configuration

...

A header file for the resulting time series can be made by copying and renaming any of the input header files (*.hdr) and adding an extra line to define the number of file blocks:

	NBLOCKS		4

If the header contains a definition of NBLOCKS larger than 1, an extra file (*.tim) is required to define a timestamp per block in the format YYYYMMDDHHMM:

200001011200
200001011300
200001011400
200001011500

Note: The way the NBLOCKS parameter is added to the header file (*.hdr) and an extra file with time step definitions (*.tim) is added is practically the same as how these are used by the PI-BIL parser, but one should realize that the order in which BANDS (parameters) and BLOCKS (time steps) are stored is not the same, so the files are not compatible unless either NBANDS or NBLOCKS equals 1.

Configuration

	<location id="SATH_AFRICA" name="SATH_AFRICA">
		<shortName>SATH_AFRICA</shortName>
		<x>0</x>
		<y>0</y>
	</location>

	<regular locationId="SATH_AFRICA">
		<description>SATH Rainfall files</description>
		<rows>702</rows>
		<columns>1002</columns>
		<geoDatum>WGS 1984</geoDatum>
		<firstCellCenter>
			<x>-13</x>
			<y>25</y>
			<z>0</z>
		</firstCellCenter>
		<xCellSize>.03</xCellSize>
		<yCellSize>.03</yCellSize>
	</regular>

<idMap >
   <parameter internal="P.obs" external = "0"/>
   <parameter internal="T.obs" external = "1"/>
</idMap>

<timeSeriesImportRun>
   <import>
      <general>
         <importType>BILBIPBSQ</importType>
         <folder>$IMPORT_FOLDER$\BSQ</folder>
         <fileNameObservationDateTimePattern>'NI_'yyyyMMdd'.BSQ'</fileNameObservationDateTimePattern>         
         <idMapId>IdImportBSQ</idMapId>
         <unitConversionsId>ImportUnitConversions</unitConversionsId>
         <importTimeZone>
            <timeZoneOffset>+00:00</timeZoneOffset>
         </importTimeZone>
         <geoDatum>WGS 1984</geoDatum>
         <dataFeedId>SATH_AFRICA</dataFeedId>
      </general>
      <timeSeriesSet>
         <moduleInstanceId>ImportBSQ</moduleInstanceId>
         <valueType>grid</valueType>
         <parameterId>P.obs</parameterId>
         <locationId>SATH_AFRICA</locationId>
         <timeSeriesType>external historical</timeSeriesType>
         <timeStep unit="day"/>
         <readWriteMode>add originals</readWriteMode>
         <expiryTime unit="day" multiplier="30"/>
      </timeSeriesSet>
         <timeSeriesSet>
         <moduleInstanceId>ImportBSQ</moduleInstanceId>
         <valueType>grid</valueType>
         <parameterId>T.obs</parameterId>
         <locationId>SATH_AFRICA</locationId>
         <timeSeriesType>external historical</timeSeriesType>
         <timeStep unit="day"/>
         <readWriteMode>add originals</readWriteMode>
         <expiryTime unit="day" multiplier="30"/>
      </timeSeriesSet>
   </import>
</timeSeriesImportRun>