Just a brief note to say that the open source GIS MapWindow has reached version 4.4, and the new version is definitely a worthwhile upgrade if you already have the program. A whole bunch of shapefile editing capabilities have been added, there’s now an Undo function in the shapefile editor you can turn on, higher-resolution raster export, plus bug fixes and a few other features. I plan to do a video in the near future demonstrating these new capabilities, similar to the ones I’ve done before on MapWindow.
Archive for the 'GIS' Category Page 17 of 23
SAGA GIS (System For Automated Geoscientific Analyses) is a free raster/terrain-oriented GIS program (some vector functions), with a modular structure that makes it easy to add additional capabilities. After being in release candidate mode for about a year, the final official version 2.0.0 was released about two weeks ago, replacing the previous version 1.2 stable release. Probably the biggest change is the move from Windows-only to a multi-platform release supporting both Windows and Linux. A quick examination of the module packages shows that a few new modules have been added, but most are unchanged. However, module management has been significantly improved with the addition of a “Modules” tab to the Workspace window, and in general it’s easier to pull up data in the new version.
Best of all, there’s been a huge improvement in documentation. Version 1.2 had a good introductory 200-page manual that’s still worth downloading and reading, but many of the modules had virtually no documentation at all. Version 2.0 now has a terrific 400-page manual, available at the SourceForge download page along with a copy of the demo data used in the manual. And while even the manual doesn’t cover all the functions of the different modules, clicking on a module in the “Modules” window and then clicking on the module’s “Description” tab brings up a cursory description of the module and the input parameters. While it will still take some time to figure the module’s operation out, that’s still better than the way it was with version 1.2. A listing of the available modules is at the bottom of this post, after the fold.
It’s a good thing there are now two good manuals, because program function takes some getting used to. SAGA uses its own raster grid format (.sgrd for version 2.0), so grids in other formats have to be imported into the program (and exported into other formats as well). Setting parameters for individual data layers also takes some getting used to. But given the huge number of module functions available in this program, it’s worth spending some time figuring out how to use it. I hope to cover some of the modules not documented in the manuals in future posts (I’ve already covered using SAGA to convert raster graphics to shapefile format in this post).
A list of modules in SAGA 2.0 follows below the fold (taken from the user manual).
SlashGeo links to a website that, like a number of others, offers services to convert graphic images and vector data into Google Maps, Google Earth, and Virtual Earth formats. There’s certainly a niche for services like this, especially if you don’t have a lot of background in working with geographic data. But if you have even a little bit of that background, you can save a lot of money by doing it yourself.
1. Converting PDF files to Microsoft Virtual Earth format requires first converting them to a graphic format like JPG or TIF, which you can do with for free with PDFCreator. Next you have to georeference them, assigning coordinates to the individual pixels in the image. I’ll be covering a number of free ways to do that in the future, but for now, it’s enough to say that you can georeference and image with the free GIS program MapWindow, or with MicroDEM. Finally, to convert the georeferenced image to Virtual Earth format, you can use Microsoft’s free MapCruncher utility. Saves about $499 versus outsourcing it, at the cost of a just a little time.
2. For plotting vector data like shapefiles on Google Maps, you can use the free utility Google Map Creator. Need to convert AutoCAD files to shapefile format? There’s a free plugin for MapWindow that lets you do that. Saves you $349 over outsourcing it.
3. Finally, for putting GIS Data into Google Earth format, there are a number of free or cheap options that let you do that. And to convert PDF files into a Google Earth format, use the process outlined above to convert a PDF to an image, and then georeference it. If you need to convert the image from UTM or some other coordinate system to Google Earth’s native coordinate system of latitude/longitude, you can use a free utility like GDALWarp (also to be covered in the future on this blog). You can then use a cheap ($20) utility like Valery Hronusov’s SuperOverlay to convert that image, or any georeferenced image, to a tiled Google Earth format. $20-50 in software costs, at most, versus an outsourced cost of $199-499.
BTW, if you have the need for any of these services, and don’t feel comfortable doing them yourself, email me with your requirements, and I’ll quote you a price that’ll be far less than those listed above ;-).
Another in a series of posts on free toolsets for ESRI products. Today’s sets comes from Valery Hronusov, author of such useful paid tools as SuperOverlay (a stand-alone program for creating tiled raster image datasets for Google Earth), and KMLer (an extension for ArcGIS that exports data in KML format). The free tools are only for ArcGIS, versions 9 and higher.
In a previous post, MicroDEM was used to create viewsheds from a DEM (digital elevation model), and plot them on top of either a DEM terrain image or a corresponding map loaded into the program. But it could be useful to export the viewshed data alone, either in raster or shapefile vector format, for use in other GIS programs. More generally, the need might arise to convert a general raster image of an area into a polygon shapefile. You can do this with the Spatial Analyst extension for ArcGIS, but the two together are pretty expensive. There’s a somewhat painless way to do it with free software.
Continue reading ‘Converting Raster Area Images Into Polygon Shapefiles’
NOAA’s Meteorological Development Laboratory offers degrib, a multi-platform application that downloads many different kinds of US Weather Service forecast data (e.g. temperature, precipitation, wind, etc.) from the National Digital Forecast Database. Data is available for every 3 hours for the next 72 hours, every 6 hours for the next 7 days. Degrib also converts the data into GIS formats: shapefile, CSV, NetCDF and binary float (.flt) format. Data is also available via WFS, XML, and in a graphic web browser format.
Via The Earth Is Square, which has screenshots and more
Although you view a DEM (digital elevation model) as a two-dimensional representation of terrain in MicroDEM, the program can treat it as a 3-dimensional surface and analyze it as such. Perhaps the simplest example of this is in answering the question, “What terrain can you see when you’re standing at a specific location?”, and MicroDEM has tools that let you do that.
Continue reading ‘"I Can See My House From Here": Line-Of-Sight And Viewsheds In MicroDEM’
Another set of free utilities for ESRI products, a complementary set to the ones from this previous post. This time they’re mainly for older versions of ArcView (but there’s a couple of more recent ArcGIS tools as well). Available here.