A while back, I posted on an NOAA website that mapped carbon dioxide concentrations and emissions globally and locally. The Green Car Congress website has posted about a new resource that has maps of both emissions and sequestration, real and potential, for the US and Canada.
One site linked to has PDFs of the printable version of the Carbon Sequestration Atlas of the United States and Canada. The NatCarb site links to maps, static and interactive, showing both the sources and potential sinks/sequestration sites for carbon dioxide.
Published at March 31, 2007
in data.
If you love maps, you have to see the Strange Maps blog. Unusual, historical, fictional, gastronomical, delusional, exceptional, etceteral maps, with excellent accompanying posts (and great comment sections as well).
The Relief Shading website defines “shaded relief” as “a method for representing topography on maps in a natural, aesthetic, and intuitive manner”. A review of the many resources on that site, and on Tom Patterson’s excellent Shaded Relief website, will convince you quickly that getting the best possible results requires a great deal of knowledge, expertise and time. But you can get fairly satisfactory relief shading of your maps quickly and easily using 3DEM.
Continue reading ‘Easy Map Relief Shading Using 3DEM’
A DEM (digital elevation model) essentially consists of a grid of data, where every square in the grid corresponds to a geographic location, and the value at that position in the grid is the elevation above sea level. But those are just numbers, which are hard to visualize.
3DEM is a free program that opens DEM data and lets you visualize and use it in a number of different ways. It comes with a first-rate PDF manual, available from the Help menu. Today’s post deals with just the basics; upcoming posts will cover some of the interesting ways you can use the data to visualize topography and geography.
Continue reading ‘DEM Terrain Depiction Using 3DEM’
Yesterday, I posted about the raster combining and export capabilities of the TatukGIS Viewer. But it’s also a first-rate vector file viewer as well, and can export high-resolution raster images of the vector display using the capability described yesterday.
Among the vector features of the TatukGIS Viewer are:
- Support for a large number of vector formats, including shape, E00, DXF, Tiger road data, GPX, KML, MIF, VPF, DLG, etc.
- Fast display.
- Overlay vector files on top of raster, modify transparency of both.
- A handy wizard for assigning vector display properties using attribute data.
- Standard query and selection by attribute.
- Pie and bar charts by table attribute, superimposed on the map. (Note: Do this before modifying shapefile display properties, otherwise it doesn’t work)
- Selection by point, line, rectangle, circle, polygon; intersect, touch, within, cross, overlap.
- Measure distance/area for line, polygon, rectangle, circle.
- High-resolution export of georeferenced raster image.
- Print image with options to include scale, title, or legend, either to printer or PDF file.
- User-selectable appearance themes.
- Save projects.
No editing capabilities, just viewing, but the TatukGIS Viewer is among the best free GIS viewers out there.
The USGS Seamless Server data gateway I posted about yesterday has a filesize limit per download of 250 MB uncompressed (the zipped, compressed size of the downloaded files is usually much smaller than the uncompressed size). If raster map data you’ve selected for download has a combined size greater than 250 MB, the server breaks it up into smaller segments, each downloadable as a file. If you import all of these separate files together into a GIS program, it will automatically position all the pieces together in the right place. But you might find it more convenient to combine all of the individual pieces together into a single map file with the same resolution, and still georeferenced.
Continue reading ‘Full Resolution Raster Map Combining, Subsetting And Export With The TatukGIS Viewer’
Over the next few weeks/months, I’ll be putting up a fair number of posts on software tools that work with Digital Elevation Models, or DEMs for short. A DEM is essentially a grid of an area where each point in the grid represents the elevation or altitude at that point. With a DEM, you can do things like determine the altitude and slope at a point, measure the terrain profile, make 3D views (both static and interactive), and so on. Before starting those posts, it makes sense to talk about a good source for that data.
Continue reading ‘The USGS Seamless Data Distribution System’
In an earlier post, I talked about a website that gives you coordinate data for a point in Google Maps. I’ve just found a website that gives you that information, and more, for any point within Google Maps.
Earth Tools offers up the standard Google Maps interface with position crosshair in the center, and a number of information options for the position marked by the crosshair:
- Location: Click on this, and get the position both in latitude/longitude (decimal degrees and degrees-minutes-seconds) and the UTM coordinates
- Height: Give the elevation of that location in feet and meters
- Time: Gives the local time, and the time zone relative to Universal Time (GMT)
- Sun: Gives the time for various twilights (Astronomical, Nautical and Civil), and sunrise/sunset
- Distance: Click on the “Start Measuring” button, and scroll/pan the map – you will get the distance from the original crosshair position to the new one. Click on “Stop Measuring” when you’re done.
- Places: Enter a place name to search for it from a database of 7.5 million names.
In addition to the regular Google Maps Map-Satellite-Hybrid buttons, there’s a fourth one called Contour that will supposedly overlay a high-resolution contour map on top of the Google Maps display. For my area, coverage wasn’t complete yet, more of a checkerboard pattern; YMMV.
The website also offers the elevation, time, and sunrise/sunset data via a webservice.
