Here are some results of my experiments with the graphical modeler in GRASS 6.5. Question: is the code the same for the modeler across all GRASS versions currently?
I tried to create a model that did the following steps using the Spearfish demo data set:
- convert the vector streams map to raster
- run r.buffer on the rasterized streams
- convert the raster buffers to vector areas
I did succeed ultimately in creating a model that did these steps. I ran into a number of issues, but am not sure which are bugs and which are misunderstandings of how this is supposed to work. So I’ll go through them step by step. Here is what I learned in the process and the questions I encountered.
**Data Item"
Adding data item works fine. But data items added with this button cannot be linked with GRASS command items AFAICT. You must enter a data item in the command module dialog and a data item is automatically generated. So what is the point of this button? The mouseover calls this a data item. If it is only a map, then it is probably easier for GRASS users to understand if the mouseover text said “add map to model”. If it includes other kinds of data, I do not know how to indicate this.
Command Item
Mouseover to this item is “add action (GRASS module) to model”. It would probably make more sense to GRASS users if it said “add GRASS command to model”
Once an action item has been added to the model, it opens a dialog that lets the user select a GRASS command. A GRASS command typed in command text window not recognized; the command must be selected from the combo box. The command is then written to the command window.
GRASS commands are duplicated in the combo box.
After selecting a command in the combox box and clicking OK, nothing shows up in modeler canvas.
It turns out that after selecting the command from the combobox, it is necessary to then place the cursor in the command window, after the command, and press return. But the command must first be selected from the combobox. Why have the command window at all if they must be picked from the combobox?
Clicking OK in command dialog does not make it go away. It is necessary to press the close button. The OK button should kill this dialog.
What does “parmeterized in model” mean? When it is checked, I can see no way of connecting a data item to a command item. And I can find no place to define a dummy data item into which data can be place when the model is run. There is a section on variable controls, but it isn’t clear how to use these.
Modeler Window
Input from an existing map shows up a oval with arrow to command module. But module taking output from another module doesn’t show any graphical connection. There is no way to draw a graphical connection from one component of a model another component.
After unchecking the parameterized boxes in an action item, and clicking the connector button a couple times, the modules become linked with arrows. But the arrows go the wrong way. that is, in my model, data from v.to.rast feeds into r.buffer and data from r.buffer feeds into r.to.vect. But the arrows are from r.to.vect to r.buffer to v.to.rast.
AFAICT, at the button with the mouseover text of “define relation between data and action items” does nothing graphical. It works sporadically, and when it does, it seems to generate data ovals and connect them to the command boxes. But these must be defined in the command item/grass module AFAICT.
I did not yet try saving a model, reloading it, or exporting it to Python.
Michael
C. Michael Barton
Director, Center for Social Dynamics & Complexity
Professor of Anthropology, School of Human Evolution & Social Change
Arizona State University
voice: 480-965-6262 (SHESC), 480-727-9746 (CSDC)
fax: 480-965-7671 (SHESC), 480-727-0709 (CSDC)
www: http://www.public.asu.edu/~cmbarton, http://csdc.asu.edu
I fixed data item first