From: Ernest WilliamsSubject: SUMMARY for lat/long transformations ECOLOG folks, After posting the following message, some people requested that I pass along the replies back to the list, so here they are, somewhat edited. Many thanks to all contributors; the replies helped me solve my problem. This reflects the power of the web. Ernest Date: Mon, 24 Jan 2000 13:29:15 -0500 I'm looking for software that will: 1. transform continental-scale latitude/longitude data to x/y (Cartesian) coordinates. 2. calculate the great circle distance between two points given their latitudes and longitudes. Thanks for helping. Ernest Williams, Hamilton College _________________________________________________________ TWO PEOPLE SUGGESTED ARCINFO. Date: Mon, 24 Jan 2000 14:50:27 -0500 =46rom: Petya Entcheva Hello, There is a very widely used software that ca do it: ArcInfo ArcInfo has a good "help" pages, but I'll be happy to help if you'll like...= =2E. Petya AND Date: Mon, 24 Jan 2000 15:32:06 -0500 (EST) =46rom: Jiong Jia The job will be easily done if Arc/Info and ArcView are combined. Good luck. _________________________________________________________ =46rom: "Michael S. Batcher" Date: Mon, 24 Jan 2000 14:48:06 -0500 Check out this link and see if it helps. If I recall, there are two versions of the software: a little one and a big one. I think the little one will work for you, but you should read the web page. Good luck! http://crunch.tec.army.mil/software/corpscon/corpscon.html _________________________________________________________ Date: Mon, 24 Jan 2000 17:38:13 -0200 =46rom: Friedrich Herms Dear Ernest I have this simple dos program (attach) to transform coordinates. I hope tha= t this can help you. Friedrich Herms Oceanography Dept. - UERJ Attachment converted: Macintosh HD:coord.zip (pZIP/pZIP) (0000AD04) NOTE: PROGRAM NOT FORWARDED TO ECOLOG-L _________________________________________________________ Date: Mon, 24 Jan 2000 15:17:09 -0500 =46rom: Sheryl Soucy In order to calculate great circle distances given longitude/latitude coordinates, I used the following web site: http://www.vwlowen.demon.co.uk/java/circle.htm I'm not sure who runs the web site or what the intended purpose of the web site is. I somehow stumbled across it while looking for software to make that calculation. Peter Krafft in the geography department at Florida State University also provided me with the formula for the calculation which is Cos D =3D (sin A)(sin B) + (cos A)(cos B)(cos P) D =3D arc distance between points A and B A =3D latitude of point A B =3D latitude of point B P =3D degrees of longitude between points A and B I think all of these terms have to be in radians instead of degrees. I never had to use this formula because I found the website first. _________________________________________________________ =46rom: "james salierno" Date: Mon, 24 Jan 2000 14:00:57 PST Dear Ernest, You might want to check out the US Coast Guard web page. I downloaded a program to convert loran coordinates to Lat/Lon. It may have what you need as far as x/y cartesian is concerned, Good Luck, Jim _________________________________________________________ =46rom: "ROBINSON, JULIE A. (JSC-SN3)" Date: Tue, 25 Jan 2000 08:52:48 -0600 There are several javascript tools on the web for calculating the great circle distance. I use http://www.best.com/~williams/gccalc.htm Good instructions (in the form of an FAQ) for how to do the calculations yourself (e.g. in a spreadsheet) are at http://www.census.gov/cgi-bin/geo/gisfaq?Q5.1 Spreadsheets to do both of the calculations you want (x/y and great circle) can also be downloaded from the Australian Surveying and Land Information Group. http://www.auslig.gov.au/geodesy/calcs.htm Hope this is helpful. Julie _________________________________________________________ Date: Tue, 25 Jan 2000 09:59:23 -0700 =46rom: Mike Kearsley Ernest; I've attached a program which will (I think) convert lat long data to UTM coordinates (which is a form of x-y that may work for you) and vice versa. Be aware that there are different versions of lat and long, and that you'll have to choose one (I've always used International). I can't help you with the great circle distance calculations. Mike NOTE: PROGRAM NOT ATTACHED. I USED IT SUCCESSFULLY, HOWEVER _________________________________________________________ Date: Fri, 28 Jan 2000 09:18:55 -0700 =46rom: Mike Kearsley Ernest; I found a web page with lots of information on free cartographic software: http://kai.er.usgs.gov/ftp/PROJ.4/PD.projections.FAQ The site is dated "1994" and includes lots of references to ftp download sites, so some stuff may have changed, but there are links on the page worth checking out (especially the GCTP freeware information). Cheers, Mike mike.kearsley@nau.edu _________________________________________________________ =46rom: TA32@aol.com Date: Tue, 25 Jan 2000 09:28:21 EST Mr. Williams: You might try looking on the web page: www.wellston.com for the software you are looking for. Wellston Technologies, Inc. puts out some very user friendly software (windows based) for manipulating data from GPS receivers, including downloading the data directly from the receivers as well as lat/long data handling capabilities. They have some software on the website that you can download for a free 30-day trial if you like. Good luck, Tyler Abbott tyler_abbott@fws.gov _________________________________________________________ Date: Sat, 29 Jan 2000 17:20:56 -0600 Reply-To: Jerrold Zar You might look at this paper: Zar, Jerrold H. 1989. Microcomputer determination of distance and initial direction of great-circle paths. Journal Field Ornithology 60:520-522....... _________________________________________________________ Date: Sat, 29 Jan 2000 19:13:41 -0600 Reply-To: Jonathan Stern ernest, you might check out matlab. it has a toolbox called 'mapping' that does what you require very nicely. though i need to go check out dr. zar's reference. i hope this helps. jon _________________________________________________________ Date: Mon, 31 Jan 2000 00:06:03 +0100 =46rom: Michele Scardi Ernest, I wrote a Fortran program that transforms geodetic coordinates (I mean lat/lon degrees, e.g. 38.5432=B0N 14.7865=B0E) to UTM coordinates using the WGS84 datum. If you (or other ecolog-gers) want to give it a try, just drop me a line. I can send you both the source and/or the executable. It's a program I wrote for myself and I always used it within 2 UTM zones only, but it seems that it works, although it isn't exactly user-friendly. You can also take a look at: http://www.swcp.com/csar/UTMConverter.shtml There's a nice Java UTM/Lat-Lon converter that can be useful if you only need to convert a limited amount of data. Point your browser to: http://www.utexas.edu/depts/grg/gcraft/notes/datum/datum.html or to http://geography.hunter.cuny.edu/mp/ for complete info about coordinate systems and map projections. I hope this helps, Michele _________________________________________________________ Date: Mon, 31 Jan 2000 13:46:30 -0500 (EST) =46rom: Robert Kenney The algorithm below will calculate great circle distances between pairs of lat/long coordinates. I pulled it out of one of my SAS programs, but the syntax is pretty basic. It uses lat/longs in radians, and the distance is in kilometers. Take out the 57.29578 factor to use lat/longs in degrees, and take out the 1.852 factor to get distance in nautical miles. (Hi, Jon!) DISTANCE =3D 1.852 * 60 * 57.29578 * ARCOS((SIN(LAT1) * SIN(LAT2)) + (COS(LAT1) * COS(LAT2)) * COS(LON2 - LON1)); Cheers, Bob