The CDROM Contains 3 Directories. to Install GOB, Create a Folder on Your Hard Drive With

Installation

The CDROM contains 3 directories. To install GOB, create a folder on your hard drive with whatever your name you wish and drag the 3 directories into that folder. To run the program, first navigate to the new folder you created, then to the subdirectory called Program. You should then see the application called GOB or GOB.exe. Double clicking on the application will start the GOB program.

In order to use the GOB help buttons, you must define the GOBHELP environment variable which points to the location of the HelpFiles directory. This can be done on by going to the Windows Start menu then Settings->Control Panel->System->Advanced.

You should find a button for Environment Variables. Hitting the New button will allow you to define GOBHELP as the location of the HelpFiles directory.

It should be noted that the program will run successfully on Windows machines with significant amounts of RAM and video memory . Although minimums have not been established, the program should perform well with 256 Mbytes of RAM and 32 Mbytes of video memory. More is better.

Running GOB

The program requires a digital elevation model (DEM) in ENVI format. Because a DEM does not lend itself to easy visualization, other coregistered files such as shaded relief images and a TM scene are much more appropriate for using as a display image. The TestData directory includes a 3 banded Landsat TM scene and a shaded relief image of the same area contained within the DEM. The steps to get started are provided below.

1)  Define a working directory. This is where the data resides on hard disk. Click on File->Set Working Directory. A dialog box will come up. Navigate to the TestData directory then click OK.

2)  Define the DEM file. Click on File->Associated DEM File. A dialog box will come up showing the contents of the TestData directory. Click on either of the DEM_sub_filt icons or files.

3)  Define the parameter file. Click on File->Flowgo Parameter File. A dialog box will come up. Click on the gobparams or gobparams.txt file. The contents of this file can be viewed and edited by clicking on Parameters->Edit Parameters. A dialog containing several tabbed pages of parameters should appear. To change any of the parameters, double click on the value of the parameter. The value should move to the left of the field. Edit the value then hit return. The value should move to the right of the field. Then hit “Apply” or “Apply and Close”.

4)  Display an image. Click on Display->ENVI file. A dialog containing the images within the TestData directory will appear. Choose TM_sub and then OK. TM_sub is a three band TM subscene containing band 5, 4, and 2 as the first three bands. A dialog will appear. At the top of the dialog click on “RGB”. In the Band(s) field, you should type “0 1 2”. This places TM band 5 in the Red, TM band 4 in the Green, and TM band 2 in the Blue”. Leave the scaling as is and hit ok. In a few or many seconds, the TM scene should appear. If the scene appears too dark, repeat the process but replace 0 with –50 in the Minimum field before hitting OK. If you would like to work off of the shaded relief, choose SHADE_sub and on the Display Options Dialog, leave the Display at Grayscale rather than RGB. Then hit OK.

5)  Define a flow origin and its path. Click on Flow Model->Predict Flow Path. This opens a dialog with the DEM file in the top field and blanks for X, Y and Pixel Dimension. Set the Pixel Dimension to be 30. Then click on the image at the position in which you wish to start the flow. The x and y coordinates of that point should now appear in that dialog. Click on the Drain box. This will take several seconds the first time. Subsequent locations and drains will go much faster. The drain path will show up as yellow.

6)  Do the GOB. Choose Flow Model->Start Flow Model. This will open a dialog box. The first field allows you to define the path and name of an output ASCII file which contains increment by increment updates of a large number of parameters for each model run. Hitting GOB will start the model. The extent of the lava flow will appear as red over the yellow drain path. The dialog will have some results from the model although much more detail resides in the Output ASCII file.