The Moderate Resolution Imaging Spectroradiometer (MODIS) is a low-to-moderate resolution multi-spectral imaging system currently in operation aboard two NASA satellites, Terra and Aqua. Both satellites are acquiring imagery on a continuous basis, and NASA has created a website that allows access to near-real time georeferenced imagery from both satellites, as well as archived imagery from previous days.
Archive for March, 2007 Page 2 of 5
The National Oceanic And Atmospheric Administration (NOAA) has a new Carbon Tracker website up that plots carbon dioxide concentrations and emissions globally and locally, and by time. Here’s a map of weekly mean carbon dioxide flux (emissions) for the US from January 2005:
A useful information resource for those interested in anthropogenic global warming (AGW).
Printing some maps on a standard 8.5″x11″ sheet of paper doesn’t make a lot of sense; the scale can be so small that you might not be able to make out any details at all. But even medium-format printers (capable of 13″x19″ paper sizes) are expensive, starting at about $300; large-format printers capable of handling paper in widths of 24″ or greater can easily run over $2000. Print services can be expensive as well, with a single large map costing anywhere from $25 to $100 to print. But there is a way to make printed maps larger than the largest paper size supported by your printer: break the map image up into smaller sections which are printed onto individual pages, trim off the edges, then assemble all the pages together into a larger map. This is sometimes referred to as “poster printing”.
There are several free ways to do this. First, some printers support poster printing; check the Preferences section of your printer driver to find out. Here’s an example of that for my Canon iP3000 printer:
There’s a free Windows program called Posteriza that will chop an graphic file like a map into smaller segments, and then print each segment on a single sheet of paper. This program offers more control than the typical print driver – you can crop the original image, see a preview of how the original picture will be segmented, and add both text and graphics to the poster image as well. And you can save the settings in a file for future use:
Finally, the excellent free image organizer and editor Picasa has the ability to chop up a graphic into segments that can then be printed as individual pages and re-assembled as a poster. Select the image, then choose Create => Make a Poster from the menu:
You’ll only have the choice of two paper sizes, 4×6 and 8.5×11. And you can only specify the percentage of enlargement for the original, with no preview. But Picasa gives you an option the previous two methods don’t: to have the printed image segments overlap each other slightly (by checking the “Overlap tiles” box). This will give make trimming the images less critical, since with some overlap you can make a small cutting error and not lose any part of the final map. After you click on OK, Picasa will create the image segments and put them into the same folder as the original image; you’ll still have to select and print them manually.
Picasa has another geographically-related use: you can Geotag your pictures using Picasa and Google Earth, view them in Google Earth at the tagged location, or export them to a Google Earth KML file. See the tutorial at Ogle Earth for step-by-step instructions.
There is another way to do poster printing with one additional useful feature: the ability to set the scale for the printed map. I’ll cover this in a future post.
hablandodesigs links to the Mexican National Atlas, posted online by the National Autonomous University of Mexico’s Geographic Institute. Large-scale JPG scans of pages from the published volumes, slightly marred in some cases by not using de-screening during the scans. Map categories include General, Historical, Societal, Natural History, Environmental, Economics, and International Relations. En Espanol, of course, but even this gringo was able to make his way through the site and the maps. Here’s a subsection of one of the maps, showing the geology of the area around the northern Gulf of California.
Google Earth’s native coordinate system is geographic (latitude/longitude, WGS84). So if you have your coordinates in UTM (Universal Transverse Mercator), you need to convert them to geographic first before using them in Google Earth. There’s a small utility that makes using UTM coordinates in Google Earth a lot easier.
UTMFlyer allows you to enter UTM coordinates, and go directly to that point in Google Earth. No installation program, just unzip it into a folder. If it complains about missing .bpl files, you can download them here, and put them either into the same folder as the program or the Windows/System32 folder. Start up the program; if Google Earth isn’t running it will be started up automatically as well. Basic interface is very simple:
Choose the UTM zone and hemisphere (N or S) with the dropdowns, and the UTM coordinates, Easting and Northing separated by a comma. When valid coordinates are entered, the airplane logo will appear at the right – click on that, and Google Earth will go to that location.
But wait, there’s more. The checkmark/exclamation icon is a dropdown menu. In addition to links to the software home page, an info page on UTM, and setting the altitude you fly to, there are also links to “Conversion” and “Extent”. Select Conversion, and the program window expands and adds several option tabs:
Here, you can enter UTM coordinates and convert them to latitude/longitude (WGS84 only), or do the opposite conversion; clicking on the airplane icon will once again take you to that location. And there’s a bonus decimal degree to degree-minute-second converter (and back again).
Selecting “Extent” from the menu gives you this window:
Which shows you the extents of the current view in Google Earth in geographic coordinates.
Two previous posts talked about the coordinate converters CorpsCon and GeoTrans. Both are very good, but are large in filesize, and not necessarily user-friendly. There are two other freeware coordinate converters that are smaller in download size (1.7 MB and 0.9 MB), and fairly easy to use for single point conversions.
Continue reading ‘Coordinate Converters III – Two Freeware Converters’
Here’s a useful tool for identifying which USGS 24K topo quad covers a specific area in the US in Google Earth; it even gives you a handy link to download a GeoTiff of the map from the Internet Archive.
DDS Mapfinder is a KMZ file that opens up in the places pane in Google Earth. Read the warnings and instructions first before using it – if you try and open topo grids for all the states, you may crash Google Earth. Check on an index for a particular alphabetical group of states, and rectangular grids will open on top of those states:
Continue reading ‘Identify And Download USGS 24K Topographic Maps In Google Earth’
Note 1: See this series of posts for info on converting shapefiles to KML format.
Note 2: The current version of the program has a bug that doesn’t let you select a file. The author has indicated on the website that a new version should be out soon, but until then, you may have to use the approach described in either this post or another post. Also available now is an online KML to shapefile converter.
In two previous posts, I covered several multi-step hacks for converting Google Earth KML files to shapefile format, since there wasn’t a single-step free approach to my knowledge. Well, there is now, and it makes the process a lot easier.
Continue reading ‘The Last Word (For Now) On Converting Google Earth KML Files To Shapefiles’
