Notice to all visitors and members of the Train-Sim.Com message forums: If you plan on using a signature banner in your posts, we would like to remind you that there is a maximum size for banners. That maximum is 450 pixels wide by 120 pixels high, and not to exceed 25k. Your compliance is appreciated. FORUM RULES Problems? There are two common reasons for problems with logging in and posting messages. The first is that you are running a firewall that prevents your messages from being sent to the server. The other is that you have cookies disabled; the DCForum software requires cookies to work properly.
Hello There I have read some rumours about a devitation of aprox 10% in lon/lat possitioning in the route editor, Does anybode know more about this? is it true or some misunderstanding?Sorry for possible typo's
I know this much. DEM data uses a slightly different coordinates than topographic maps. If you are using DEMEX for North America, put in an offset of 22 meters N, and 92 meters E. Cal Rasmussen Beaverton, ORColumbia Gorge Route (The Dalles Dam 80% done)
Cal,That is generally true in the area that you (and I) are modeling, but not generally true and varies by quad. There are different datum used by mappping systems. Because MicroDEM converts everything to a 1980's world datum (too lazy to look up the exact date and name), DEMEX (which started out needing MicroDEM) also makes that conversion. Most USGS topo quads and the information derived from them, including DRG files and raw DEM files is in NAD27, the North American Datum of 1927. All of the quads include the shift necessary to convert that particular quad to NAD83. NAD83 is essentially equivalent to the world datum used by DEMEX. So if you have NAD27 data, you have to convert it to NAD83 to use it on routes generated by DEMEX.JohnCS, if you read this, would it be possible to have an option in DEMEX to leave the data in NAD27?David Beach.
Datums still make my head spin. IIRC one of the real reasons DEMEX forces everything to WGS84 is that is the datum used by the RGE in defining the tiles - much much easier to keep everything in the same frame of reference.Actually the better solution is to datum shift your marker file to WGS84. On the long old to-do list that is.Thinking of that, there may be a workaround available - gotta do a little research in Microdem......
Here is a 98.6% probable hack.....Microdem doesn't encode the datum used in a MD DEM file, and just saves it with whatever datum is set as the primary datum. DEMEX just assumues this is WGS84 for lack of anything better.Load an individual dem in Microdem. Change the Microdem primary dataum (under the options/maps tab) to whatever datum you want, ie NAD 27. Save the dem as a MD DEM file. You can now load this dem in DEMEX and it will retain the NAD27 (or whatever) coordinates.Note this will only work with a native format dem, ie SDTS - you can't really fake it out in Microdem with a dem already saved in MD dem format.One caveat: Don't even think about merging dems across a UTM zone boundary in the latest DEMEX with this method. The old method of generating terrain on one side then the other 'might' work, but I have concerns.
I believe that the route editor is right on, when it comes to lat/long, as long as you have your datum in order. This is a big caveat, however. It took me many moons of headaches and smashing things against walls to get this right, however, now I am blessed with a perfectly aligned marker file that makes the track laying so much easier, I can't even begin to say. The WGS84 datum is the one you want, which is the one DEMEX uses, so your marker file needs to be in that datum.MarkMoffat Road from Tabernash to Craig (30% of track laid)
