Running FILL and FLOW

Examples | FILL options | FLOW options | Configuring TerraFlow

FILL takes as input an elevation grid and outputs a flow direction grid directions.asc and a filled elevation grid elevations.asc. FILL can also create a special file called the flowStream which contains all the information required by FLOW (filled elevations, flow directions) but in the internal format of TerraFlow. FLOW takes as input the flowStream produced by FILL and outputs the flow accumulation grid cnew.asc.

Before running TerraFlow the user should set two environment variables:

Example:

Space requirements: Make sure there is sufficient available space in $OUTDIR to hold the three output grids elevations.asc, directions.asc and cnew.asc. Make sure there is sufficient available space in $AMI_SINGLE_DEVICE to hold the TPIE intermediate files (approx 40N bytes for FILL and approx 50N for FLOW, where N is the number of cells of the input grid).

Example runs

Assume that the input DEM is /data/testdem.asc and the amount of available memory on the machine is 100MB.

The user has the option to run FLOW without running FILL first. Say for instance that the filled elevation grid, the flow direction grid and the flow accumulation grid were computed with other software like ArcInfo, which uses D8-type algorithms (i.e. pushes flow downslope using SFD). Running FLOW results in a different flow accumulation grid computed by extending the input flow directions to all downslope neighbors.

Example:


FILL options


FLOW options


Configuring TerraFlow

TerraFlow can be configured by setting/unsetting flags in the file stepConfig.H.

Things which can be configured include:

Here is a sample of stepConfig.H. For more info contact {laura , rajiv}.


<laura@cs.duke.edu>
Last modified: Thu Apr 19 01:09:00 2001 by laura.