My question could have been thought of as long and included almost too much info, but basically I was looking for way to draw great circle routes from origin/destination airport pairs. It took me some time to sift through the replies on this one, but I recieved some great responses, which included a variety of code and helpful tips. I decided to go with a combination of Access VBA and a MapBasic program given to me by David Haycraft, to tackle this problem. The data is prepped in Access via VBA and a few queries to place the number of flights into each individual time buckets. Next, the MapBasic program takes coordinate pairs from a database file, coordinate pairs have to be in float type, and then creates the great circle routes in whatever projection that you choose. It really works slick and is fast. If other folks are interested in the script, you can download it from here: http://www.acslink.aone.net.au/actaa/iaa.htm Look for the cre8line.mb file to download. The following are some of the folks who helped contributed. David Haycraft Robert Crossley Chaz Tompkins Paul Jones Bill Huber Vince Angelo Chuck Dillon Original Question: I was just pulled into a project to look at a variety of aircraft in the US and other parts of the world and map the routes for my customer according to their guidelines. The guidelines include analyzing airline traffic routes by geographic region, aircraft type, operator (America, Delta and so forth), Origin and Destination pairs, Route length (time in air), Frequency of flights (daily, weekly, monthly, annually) and by the expected growth factor. A lot of different things to think about. The airline data comes directly from the OAG database, in which the airlines enter in the information that is compiled by the makers of this database and it is not cheap. There is a MapInfo tool that you can purchase for $800 that will make a map of the data you pull from the OAG database. The program takes the CSV data and uses great circle distance to create routes and airports, however, there are some errors in the program. I have found out that when you have more than one origin, destination pair, say ATL (Atlanta, GA) and ORD (Chicago, IL) and with the same operator (say Dl for Delta), the two or more records are lumped together into one record and the aircraft type (767, 763 or 764) is summed into one value as well as the number of flights flown for that time period. This seems entirely wrong to me, so I need to figure out a way to make sure the data is not compromised like this and keeps its integrity. So, to make sure that this does not happen, I cannot use that program, instead, I would like to be able to create flight routes that utilize the Great Circle algorithm. We all know that airplanes do not fly in a straight line, if they did, we would have some major problems on our hands here. I can grab the data I need, and then create straight line routes after I grab the x,y's from the Origin and Destination pairs, but how do I bring the great circle calculation into the mix. My idea was to start a line at the origin and then move toward the destination by drawing a line with a node placed every 50 to 100 nautical miles. I understand that to figure out how to get from the origin to the destination, you need a bearing to help you get to the destination and this chages based on the distance from the origin and the distance to the destination. How can I draw polylines that takes all of this into account and has anyone ever done this before. Our ultimate goal is to wirte a VB or VBA program that will read in the CSV file, pull the Origin/Destination pairs from an airport file, ceate the routes using great circle and then draw them in whatever projection in either MapInfo or ArcView. I have both, but don't want to write a program in Avenue or MapBasic because it is proprietary to the software. Any suggestions out there? Todd McNeil GIS Specialist Aeronautical Radio, Inc. Annapolis, MD Phone: 410-266-2302 Fax: 410-266-4010 E-mail: [EMAIL PROTECTED] _______________________________________________________________________ List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MapInfo-L" in the message body.
