ESRI Conservation Program Resources:

Technical Tips

(Frequently asked questions, tips, shortcuts and summaries from CONSGIS regarding GIS applications in Conservation. The first section covers technical and computer questions, the second section covers scientific questions) (Under Construction)


TECHNICAL QUESTIONS:

Hardware Configurations and Recommendations:

Recommended Minimums: 300 megahertz Pentium, 64K RAM,(Save $ on 350mz instead of 400 megahertz, there is not much difference in speed), 8-10 GB Disk Drive, CD-ROM reader (since most software and GIS data is only distributed that way), Storage: Jaz or Zip or Tape drive, Some people are very fond of the writeable CD-ROMs, (Don't get a DVD, so far it is just for movies not data), Graphics: 19" monitor, Video card should support 1280x1024 at 65,000 colors minimum with a refresh rate > 75 Hz, AGP port for graphics speed, For 3D Analyst Extension, make sure the Video card is OGL-compliant (most vendors weren't sure what this was). Go for the reliability and compatibility of a reputable direct purchase vendor such as HP, Dell, Gateway, IBM or Micron, especially if they sell it with NT and the software pre-installed and pre-tested.

"There are other limitations in your hardware such that 400 megahertz's not really better than 350, but the prices are likely much different. There is talk of a gigahertz CPU coming out in the future, but similarly the consensus is that it would only benefit someone running a heavily-used server. The difference between a 75mhz and 90mhz CPU is very large, but at the 350/400 level you probably won't notice a difference -- only in your checkbook. ...Use the money instead to buy more RAM (we have 128megs on out ArcView Machines) or maybe a zip drive. We use the zip drives for everything from file transfer to personal backups. Now or in the future you might consider a CD-ROM recorder (~$450). We use a lot of Digital imagery and find the CD burner invaluable for making backups and sharing data. Blank CDs can be had for about $2.00 each. the CD-R can always be added to the system later. "

"As for equipment, buy as much memory as the machine will hold. Win NT, unlike Win95, will utilize as much memory as can be stuffed in. The size of the hard drive depends on network space and file size worked with, anything around 6.4 should do you well. Drive prices fall quickly, so more can be added later cheaper than it would have cost you up front. Programs usually dictate the processor. If you will be running ArcInfo or graphics software the I would get the fastest one possible. Really anything above 300 will give you the performance equivalent to most UNIX systems out there. "

TNC is fond of extended service agreements: "We purchase an extended service agreement for $99 (one time cost), which gives us three years next-business-day onsite service for any hardware problems. This even covers our remote areas in Texas. "

Almost everyone recommended switching to NT, but keeping a machine in Win95 or dual boot Win95 and WinNT for troubleshooting installation problems, allowing you to rule out operating systems as the cause of a product that isn't working. 90% of Win95 software runs on NT. Home software, particularly games, is least NT supported, business software is best supported. Pluses included, NT more stable than Win95, can run full version of ArcInfo on WinNT (much better to use than PCArcInfo though more expensive), networking almost no different than setting a Win95 machine, running ArcView 3.0 more stable on WinNT Negatives, WinNT a little more expensive (was found to be only $99 more on some machines) and a little more difficult to configure, some items like scanners may not yet have WinNT drivers, also check into GPS compatibility if you are using one.

"The long answer is that Win NT is a much more stable working environment environment than Win 95 or 98 could ever hope to be.. Some software may have to be changed depending on what you use. Most software designed for Win 95 and 98 will run in the NT 4.0 environment. The bonus is, if you can afford it, Win NT will run the full version of ArcInfo "

"A lot of win95 software doesn't say it will work on NT mainly because the maker hasn't had a chance to test it or has found some NT platforms that won't run it but hasn't had time to fix them yet. I find that most of the time they'll run ok on your NT platform, and it helps to have a major name-brand system. Even when they don't support NT, it is often only a matter of months until they release a driver that does. I got a scanner that wouldn't work on NT and found that their SCSI version, for $10 more, did support NT and just swapped for that. "

"With today's prices on storage, for cases like this, you can consider running a dual boot system. Right now, I can run Win 95 or NT depending on what I need. Well, the only reason, for running Win 95 right now, is because of the scanner that I'm using. HP didn't have the driver for the HP 5100c scanner. This might be the same case with the GPS input. Maybe something even easier is to keep an old computer (just one) running Win 95 for special cases like this. "

Running PC ARC/INFO and ArcInfo for NT on the same NT machine: When I did this I found that there is a single environment variable for calling to the "Arc" startup program that is shared on both programs, with ArcInfo for NT taking priority. After installing PC AI you will find that running PC AI will only start Arc/NT. I am working on a batch file to get around this but for now simply open a command window (since PC AI is command based anyway), navigate to your PCArcinfo \cmd subdirectory, and type in "scrwin x". This forces the command parser to default to the current directory before searching the environment, which allows it to find the PC arc processor first.

 

SCIENCE QUESTIONS:

Uses of Aerial Photography for mapping vegetation and wetlands:

Q: "One of our tribal biologists is planning to do a wetlands mapping project to update the National Wetlands Inventory for lands within the valley of the Hoh River. She wants to have a flight done with infrared photography, but needs to know more about it. For example, what time of year is best? And does canopy cover make as much of a difference with infrared as with color photography? Although the NWI was done at 1:24,000, is this scale sufficient, or should we go with a smaller one? Any advice on the matter would be appreciated. "

A: "Your questions re: aerial photography raise lots of complex issues. Different species leaf out at different points in the spring, so you may want to time your flights to capture those. Scale depends on what level of detail you want to do your mapping. We used 1:40,000 CIR photography and were able to map vegetation at a resolution of about .5 acres. I would suggest using existing aerial photography to do your mapping. There should be both color and black and white imagery. The key is to transfer this to some base imagery for analyses-- hence the beauty of GIS. Once you've mapped wetlands, you may want to do your own flights to map specific types of wetlands or other features more precisely. You can capture a lot with existing photography and then refine what you need, if you need, with your own flights. There's a lot of data out there! "

"To get the best wetland boundaries, springtime, leaves-off, color infrared imagery is best. Whenever the water levels are highest, but before the leaves come out. In New England that's April, but it may be different where you are. If you are more interested in wetland community types (ie. species composition), having the leaves on may be better, but the boundaries won't be as accurate, because they're obscured by leaves. Color infrared (CIR) imagery works best in both cases because, a) water and wet soils show up very dark, and b) you get more distinct signatures between different vegetation types (ie. more shades of red). Stereo viewing is also important because slight changes in elevation are generally what separate wetlands from uplands. In terms of scale, I believe most NWI maps were done from 1:80,000 photography (though they may be using 1:40K NAPP photos nowadays). The delineations were then "zoom transferred" onto 1:24K USGS quads. 1:24K photos would probably be fine, however, if you're trying to relate the delineations to parcel boundaries, you may need larger scale imagery, such as 1:12K that is used in Massachusetts and other states. Of course, the larger the scale of photography, the more photos you will need to interpret, and thus the longer the project will take... "


Text, Compilation & web design: Charles Convis, ESRI Conservation Program, July 22, 1997


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