I’ve downloaded and “installed” the GlobeXplorer ImageConnect utility for AutoCAD, but already am getting the impression I won’t like it much. It is labeled prominently as “free”, but when you find the real meaning of the word, it means “free 14-day trial” with watermarked imagery.

And “installed” means putting the files in the Program Files directory, telling you they’re installed someplace else (C:\GlobeXplorer\ImageConnect), and then telling you to add that incorrect path to AutoCAD’s search path. Oops.

And what’s this with the length of the actual path? C:\Program Files\GlobeXplorer\ImageConnect for AutoCAD?

And even after ignoring those disjointed directions and using APPLOAD to load the LSP and ARX files, I’m still having no success. Ahh, the problem becomes clear. The program was last updated in 2003, explicitly mentions support for AutoCAD 2000, 2000i, and 2002. I’m running 2005.

I’ve left a message for Tech Support, so we’ll see what happens tomorrow.

I’ve explored the Earth Explorer application just long enough to discover it doesn’t have any application for anyone doing civil planning of any kind. Max resolution is 1km, and there is no georeferencing support in it at all. It also doesn’t support the SpaceBall, so it’s been uninstalled.

Trying Keyhole NV, I’m also disappointed that it doesn’t support the SpaceBall for 3D navigation, doesn’t offer any of the high resolution aerial photos I’ve found on the USGS site, and although allows me to overlay images I already have, doesn’t support GeoTIFF, thus requiring me to manually register the image by changing its transparency and fiddling with the image handles at the edges and corners. Yuck. On the plus side, it’s got a plethora of vector and POI overlays, including accurate local roads, gas stations, schools, etc. This feature will be a big help in planning for Field Day, and will speed up one of the data collection efforts—building a location overlay for our APRS mapping with the local hospitals, fire departments, police stations, ATMs, restaurants, and a few other things that might or might not be in the Keyhole database.

GlobeExplorer looks a bit more promising. It is not a 3D program, and its primary interface is a difficult-to-use Web page that lets you order prints and electronic images at somewhat reasonable rates. But the images are JPEGs, not GeoTIFFs and there is no indication if they are provided with georeferencing data. On the plus side, the company offers plug-ins for CAD and mapping software that might just offer that functionality, so I’ll be taking a closer look at its ImageConnect software for AutoCAD later this week, hopefully.

For now, though, I need to recover from the late night at the WordPress launch party.

After successfully instructing Global Mapper to download the high-res color aerial photo I had struggled with downloading and importing via USAPhotoMaps and the USGS site, I’ve now been able to match it up with the DXF contours I exported from AutoCAD, and get an initial 3D rendering of the terrain.

I’m not real happy with the results, however. The image and contours don’t align exactly, and moving things in GM is more difficult than it would be in AutoCAD. I think Global Mapper may turn out to be invaluable for data conversion and some visualization, but for now, it’s time to begin looking at more sophisticated tools. This is a case where having a command line would really make things a lot easier.

And while I can view the terrain in 3D, the user interface and export options are cumbersome. There is no support for the SpaceBall, the zoom/orbit controls are a bit awkward, and the 3D view defaults to a high vertical exaggeration factor, with no indication of what the factor is. I also can’t export to a movie or VRML file, and both the resolution of the texture map applied to the terrain and the extents rendered in 3D vary according to your zoom level, making it difficult to get high-quality images in the separate 3D window.

I’ve installed @Last Software’s SketchUp application, with a goal of determining how suited it is to the task of site planning. Having spoken with the company at MacWorld, I’m not sure it has the necessary features yet, but they are planning on expanding the ways in which the application can be used, and this will make a good benchmark for that task.

Launching it for the first time, I’m presented with a Windows Firewall warning that the application is requesting access to the Internet. I’ve not seen this warning before with any other CAD software, so we’ll have to see what feature triggered the warning.

I’m able to import both the GeoTIFF and DXF contour files, but there are no provisions for aligning them or even ensuring their coordinates are preserved. This was expected, given my conversation with the company. The SketchUp ESRI ArcGIS extension does offer the ability to georeference SketchUp models in real-world coordinates, but since I don’t have ESRI’s GIS software, that doesn’t do me any good at the moment.

So, at the moment, SketchUp’s capabilities are not sufficient for me to use it for this phase of the Field Day planning. I’ll give it another try down the road, though.

After taking a second look at the USGS National Map interface, and after struggling with getting the JPEG output from USAPhotoMaps to align with anything, I’ve decided to not recommend USAPhotoMaps for anyone wishing to extract an image with coordinates.

When the author adds support for GeoTIFF, or any other format that includes the coordinates, projection, and datum in it, then I’ll change my mind.

I shouldn’t have to play guessing games importing an image because the software that created it decided to use a format that leaves out critical metadata.

With Global Mapper, I can import the GeoTIFFs that I downloaded from the USGS—including both the aerial photo and the elevation data—and they just magically align, giving me a high-resolution photo draped over a low-resolution terrain map. I expect my 2-foot contours to produce better results once I figure out how to perfect the terrain generation settings, but this is a quick-and-dirty way to get an initial view of the site.

And, as Mike from Global Mapper reminded me, his program can perform the same feat, and download images from TerraServer. The user interface isn’t the best (you can draw a window of the area you wish to download, but only on a smaller thumbnail image in the dialog box, not the existing map window), but it resulted in exactly the image I wanted being added to my map almost instantaneously.

From briefly exploring the four different digital map download interfaces the USGS offers, I have pretty much ruled out DigitalEarth and the National Atlas. The former has a user interface so cumbersome to use for the casual browser that it’s useless, and the latter simply doesn’t have the data I’m looking for. So that leaves The National Map and the SDDS.

The National Map has a home page that is more visually appealing, has a clearer description of what its purpose is, and even sports a nifty logo.

Using the map at first seems to be simple. You’re presented with a relief map of the U.S. and can zoom and pan in it, with the default layers including highways, surface streets, and a grayscale shaded relief. Unfortunately, the layer control is in a frame that can’t be resized (frames are evil!), which makes navigating the layers a little difficult. Turning on road labels and a few hydrology layers results in a better understanding of the map, and a fairly reasonable presentation. Unfortunately, there is no way to capture a vector version of the current map view, as SVG or DXF, for example.

I found it easy to get the DRG quad images to appear, but there is no control over the order in which the layers are drawn, so it’s impossible to specify that the shaded relief be drawn on top of the photos, or blended with them. And this time, I found two different, but nearly identical high-res color images, clearly made from the same original. One (San Francisco-Oakland 2004) was sharper, but the other (Urban Areas) had richer colors. Selecting both the NED elevation data and the color photo for download proved impossible, and selecting each individually still required downloading two files separately—the metadata and the actual image. The link to the metadata failed, and since the download is always of the current display and the image was wider than I wanted, the raster image download was delivered in two pieces, split right in the middle of my desired area. Moving the split required me to “center” my desired image on the right side of the rectangular window. I can’t get rid of the split because each half of the image is 83MB, and the download limit is 100MB.

I selected one of the elevation files for downloading, but doing so opened the ZIP archive directly in WinZIP instead of asking me what directory I’d like to save it in.

Now that I understand how the game works, I’ve figured out how to get the map window to be the size I want (answer: resize the browser window, pan the image, repeat until satisfied), and have re-specified all the options. To download the raster image, and the elevation data in both TIFF and ArcGrid formats only took me 3 more modifications of the data request. So I’ve now got the 75MB TIFF image, and two flavors of the NED and SRTM elevation data.

Time for lunch.

The USGS has collected some amazingly useful digital images. The problem is that some of the data is accessed via FTP sites or Web sites that are little more than alphabetical lists. Others are found in graphical web mapping interfaces that are perhaps the best proof of why the move to Web-based software is detrimental to usability and our society’s technical capabilities.

A further problem is that our tax dollars have already paid for the collection of this data, yet the USGS seems intent on making most of it available only for fees to be determined by the private companies that have access to the best data.

For this project, I need a color aerial photo of the Bayfront Park, and terrain data for the 4 kilometers surrounding the park (for RF propagation).

Confusingly, the USGS has numerous methods for downloading this data, including The National Map, the National Atlas, the EarthExplorer, and the Seamless Data Distribution System, with no clear indication of which system is the best for any particular purpose or data type. And with all of them, there is very little information about what each type of data offers; at least not presented in a way that is quick and easy to digest.

What is extremely troubling is that the USGS is about to delete vast amounts of data from its online database—the entire Digital Elevation Models (DEM) and Digital Line Graphs (DLG) data sets. While these are ostentiably being replaced by newer, better data, the removal of historical data is always troubling, not all current software can handle the new SDTS data format, and there is some question as to whether the newer data—specifically, the NED data set—is as good as the older data.

In the following posts, I’ll comment on how easy it is to download data in useful data formats from these sites.

Since I knew vanilla AutoCAD wasn’t up to the task of merging 2.5D contours with an aerial photo to create a cool 3D map, I set about deciding what program should be the first obvious candidate to test.

Since I was ultimately getting the imagery from the USGS, it made sense to see what they offered. The answer is not much—dlgv32 Pro is an upgrade to the earlier dlgv32 software the agency previously offered. Although the free package will do some of the things I need, its inability to export the results made it clear that its commercial sibling was the next logical choice.

GlobalMapper sells for $219, and should allow me to create many of the initial maps I need for planning, as well as providing some much-needed data conversion.

After cleaning up the contours in AutoCAD (deleting the text and filling in the resulting gaps, and correcting a few contour elevation values) I’ve exported them as a DXF file, but since there is no projection or datum information stored in an AutoCAD drawing, and since the city engineer that provided the contours couldn’t tell me either, I’m forced to resort to assume a few things and find the correct values elsewhere.

So I’ve assumed State Plane Coordinates, with the NAD27 datum, and California Zone 3. If I’m wrong, and it’s really NAD83, then I’ll have to re-do all this later. For the aerial image, I had to go digging through the USAPhotoMaps documentation to determine that the exported image was UTM Zone 10, NAD83 datum.

Yep; I’m wrong. When I specify NAD83 as the datum, the DXF file matches up with a lower-quality GeoTIFF I have of the site. I still can’t get the JPEG from USAPhotoMaps to register, so I must have guessed wrong there as well. But that task can wait until tomorrow.

My initial attempt at merging the contours I got from Menlo Park, and the aerial image I snagged from Terraserver has pointed out a few weaknesses with AutoCAD, and the need, as I anticipated, to use other, more capable programs.

The first limitation is that even though both the contours and photo have coordinates associated with them, they are different coordinate systems (state plane vs. WGS-84), and not only does ACAD 2005 provide no means of converting between the two, it completely ignores any coordinates associated with raster images (GeoTIFF images or TIFF/JPEG images with a world file). I’ve manually overlaid the photo, scaling and rotating it to get it close enough to do some initial planning, and to confirm that vanilla AutoCAD isn’t the right tool for this task.

The second limitation is a great example of AutoCAD’s lack of built-in support for 3D input devices. First, since the controller’s action is grafted onto AutoCAD, every movement of the controller pollutes the command line and the undo history with its commands, and when you stop moving, the display flashes annoyingly as AutoCAD’s “real” view is updated to match.

Second, the performance of the realtime 3D viewing sufferes dramatically once the image is attached—even if I unload the image to remove it from the display and memory. Even on my 3.0 GHz Pentium 4 and GeForce FX 6500 graphics card, the slowdown was enough that I had to revert to a version of the file without the image attached to check the contour file.

The great thing about the SpaceBall is the ease with which it lets you change your perspective. I found gently twisting the drawing around in 3D allowed me to quickly find contours that had the improper elevation and fix them. Although when I needed to highlight an out of place contour and then change the view again to get a better perspective, the highlighting disappeared—also an artifact of AutoCAD not having built-in support for the SpaceBall.

Despite being Web-based—or likely because of it—the various USGS facilities for downloading digital images are painful and tedius to use. But a free mapping application makes it easier and quicker.

USAPhotoMaps, written by a retired airline pilot, lets you download images, one tile at a time, from Microsoft’s free TerraServer Web site, creating a seamless image database that you can pan and zoom with, switching between USGS quads, ancient grayscale aerial photos, and for some urban areas, brilliant high-resolution color aeral photos. Although you must install and use a separate command-line utility, you can also export any rectangular region as a JPEG image, along with a matching world file to enable georeferencing.

It may be possible to get a GeoTIFF directly from the USGS site, but it won’t be a pleasant experience.