Latest Contributions by ElizabethGraham

Hi Fabio, Please update your expression to only have 2 open parentheses and let me know if you were then able to execute your expression successfully within the Raster Calculator.   SquareRoot(Square(0.004167)) Also, please make sure you have both your extent and cellsize set. Thanks, Liz ... View more

Hi David,  Glad to hear that you are using the environments! If you email me,   egraham@esri.com, I will send you a link to a file share so you can share your data.  Then I'll investigate the performance issue and submit a reproducible case to a developer to   try and resolve the problem. Thank you, Liz ... View more

Hi David, My name is Liz Graham and I'm a Product Engineer on the Spatial Analyst team.  I'd like to figure out why you are seeing a slowdown in performance of the Cost Distance tool. One change we made to Cost Distance between 2.0 and 2.3.3 is what is used as the default environment settings when running this tool. For example, in 2.0 the default Extent was set to the input Source dataset and in 2.3.3 the default Extent is set to the extent of the Cost Raster. When you run Cost Distance, in both 2.0 and 2.3.3, and you explicitly setting your Extent, Cell Size, Snap Raster and Spatial Reference?  If you determine that using different environment settings, and thus creating a lager raster, is not the cause of the slow down then would you please share your data with me so I can investigate further? Thanks, Liz Graham egraham@esri.com ... View more

If you have separate rasters that need to be combined into a multiband raster Composite Bands is the correct tool to use.  However, this tool should not be used inside the Raster Calculator, there is no need.  Just go ahead and use the Composite Bands geoprocessing tool from the Management toolbox --> Raster toolset (use search if you want to find it easily). ... View more

Hi Edi, When I try your Raster Calculator expression with integer inputs and a variable equal to 0.5 I am getting a floating point raster as a result, which is what I expect. I am wondering what variable type are you using for 'L'? If you use type Double your equation should return a floating point raster. To verify what 'L' equals look at the message being returned when you execute the Raster Calculator. The message has the value of 'L' substituted into the equation, make sure that this value is in fact 0.5. Example of the message being returned: Start Time: Tue Aug 23 13:36:44 2011 (1 + 0.5) * (Raster(r"layer_4") - Raster(r"1st step.img")) / (Raster(r"layer_4") + Raster(r"1st step.img") + 0.5) Succeeded at Tue Aug 23 13:36:45 2011 (Elapsed Time: 1.00 seconds) Please see the attached image of the expression I executed and my inputs. I hope this helps. Liz ... View more

Hello Craig, The Raster Calculator geoprocessing tool in ArcGIS 10 is indeed not the same as the Raster Calculator toolbar tool in ArcGIs 9.x. A more detailed explanation is avaialable in the Raster Calculator tool help as well as a blog post introducing the New Raster Calculator tool . Aside from that, a couple of key points to get you started here are: 1) The Map Algebra in the new Raster Calculator tool uses Python, whereas the syntax of the old Raster Calculator was based off of Workstation Grid commands.) 2) In the new Raster Calculator tool, you specify the expression and the output raster seperately in the dialog (in a way, similar to the old Single Output Map Algebra tool), whereas for the the old Raster Calculator, the expression and output were specified in a single line. Some things to know about Python: 1) Python is case sensitive. Each tool name must always start with a capital letter, with other letters of the tool name cased appropriately. For example, type Con, not con; And, not and; SetNull not setnull, etcetera. 2) Strings, such as dataset names, must be in quotes (for example, "caca2fm40", or 'caca2fm40'). 3) The And operator in Python performs a Bitwise And, not a Boolean And. When working with rasters in an expression, use the & operator instead. 4) When using multiple boolean and relational operations in a row in an expression, parentheses must be used to indicate the order of operation. For example, type ("caca2fm40" > 100) & ("caca2fmc" < 120) instead of "caca2fm40" > 100 & "caca2fmc" < 120. Taking one of the formulas in your post as an example: [nbgrs] = CON(( [caca2fm40] < 100 ) AND ( [caca2fmc] > 100 AND [caca2fmc] < 120 ), ABS( [caca2fm40] - [caca2fmc] ), 0 ) In the new Raster Calculator tool, the Map Algebra expression would be: Con((("caca2fm40" < 100) & (("caca2fmc">100) & ("caca2fmc" < 120))),Abs("caca2fm40" - "caca2fmc"),0) The second parameter, Output raster, is where you supply the output path and name. ("ngbrs", for this example). You can perform your analysis using multiple Raster Calculator expressions and then combine the results as follows: "nbgrs" + "nbgsh" + "nbshb" + "nbtbu" + "nbtbl" + "nbslb" Another solution is to write a small Python script, which I have attached. Just add your layers to the table of contents, right click in the Python Window and load the script, then press enter (modify the output path if necessary, currently the output path is set to C:/temp). ... View more

Hi, I have a suggestion that might help you create a valid map algebra expression. 1) To launch the Python window, click the Python Window button on the Standard toolbar, or from the Geoprocessing drop-down menu, click Python window. 2) Type the following expression, do not copy and paste.  As you are typing you will see that drop down lists appear, auto completion is available, and help* shows up in the other panel to guide you in creating expressions with valid syntax. >>> from arcpy.sa import * >>> m2w = Con(IsNull("wt1"),FocalStatistics("wt1", NbrRectangle(3,3),"MEAN"),"wt1") 3) At the end of the expression click �??enter�?? to execute the expression. For more on using the Python window: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/What_is_the_Python_window/002100000017000000/ *Note: If you don�??t see the help right click in the window, select a Help Placement (ie Bottom) and adjust the window panes until you can see the help. ... View more

Arc10 and future releases will not include the Single Output Map Algebra tool.  But not to worry, Arc10 and future releases will run in existing models and scripts which contain the Single Output Map Algebra tool.  We have deprecated the Single Output Map Algebra tool starting in ArcGIS10.   To replace this tool we have created a new Raster Calculator tool which will be available as a patch on top of prerelease There is a forum post about this but the short explanation is that we changed map algebra syntax in 10 to make it work better with python.  We can�??t have two very similar languages so the old syntax is no longer used in 10, therefore SOMA, MOMA, and the calculator from the spatial analyst pulldown menu are all gone.  To replace them all is a new Raster Calculator tool that is nicer than the old map calculator, AND can be used in a Modelbuilder, scripts and will support the use of variables. Liz Graham Spatial Analyst Product Engineer ... View more