Image / data format

[Guest jacosmit]

I ordered South African data from SA's Surveys & Mapping-department. The WGS 25m data is in a .ort format.What program can I use to read and/or convert the .ort format to a workable format to use to create a mesh?RegardsJaco Smit

[Holger 0]

Hi Jaco:nice - do I spot a new add-on mesh for a beautiful country on the horizon?I'm not familiar with the .ort format but your data should come with a detailed description of it or at least a reference where such information can be found. If you could post that information (or the link) here we might be able to give you more pointers.Cheers, Holger

[Guest jacosmit]

Hi HolgarYes, you are right. I hope to do a mesh and landclass for South Africa, and then depending from proceeds, maybe some of our neigbor contries.Here is a part of the .ort-file, seems to be text based:28075.00 3736075.00 587.24 28075.00 3736050.00 583.47 28075.00 3736025.00 580.50 28075.00 3736000.00 577.93 28075.00 3735975.00 576.26 28075.00 3735950.00 575.45 28075.00 3735925.00 575.16 28075.00 3735900.00 575.12 28075.00 3735875.00 575.15 28075.00 3735850.00 575.25 28075.00 3735825.00 574.93 28075.00 3735800.00 574.19 28075.00 3735775.00 572.68 28075.00 3735750.00 571.12 28075.00 3735725.00 568.65 28075.00 3735700.00 565.59 28075.00 3735675.00 562.80 28075.00 3735650.00 559.15 28075.00 3735625.00 557.47 28075.00 3735600.00 556.55 28075.00 3735575.00 557.55 28075.00 3735550.00 559.96 28075.00 3735525.00 562.82Thats the first couple of lines of some 1000 odd lines, and I have 13 CD's of these.

[Holger 0]

Howdy:well, that's a typical x,y,z format; the thrid value is the height and the first two the longitude and latitude, perhaps in UTM format. If it's UTM, those first two values are in meters and indicate the distance from the reference meridian. Also, notice how the second column increases in steps of 25, the spacing of your height data; pretty good!I can't believe there isn't any supporting information with those data. Did you order them through a website? Perhaps you'll find more information there.Anyway, you should be able to load the data with 3DEM or MicroDEM, even if you don't yet know the exact reference meridian. Just choose xyz ASCII terrain matrix and fill in the column/row numbers.Cheers, Holger

[Guest jacosmit]

Hi Holger and everyoneI managed to read the files using Global Mapper, then export it to a USGS DEM. I renamed the .ort extensions to .txt. Quite nice to see the results finally. Thanx for the help with this.Now, isn't there a batch utility where I can convert XYZ UTM files to a format compatible with popular FS mesh creation utilities and what utilities are available. UP to now I used to convert Dted data to FSTerrain (http://www.mnwright.btinternet.co.uk/) projects and then compile the BGL files.I believe the inf file that needs to be created should be in Arc second format, I'm not sure if the metric system is used by the inf file.Another question, my data also include Mod Clarke data in a .dat and a corosponding .hef (text) file. Althought at much lower resolution (400m, 200m and 50m), how do I read these files. Global Mapper nor MicroDem seems to want to import it. I can open the .dat file, there is a whole lot of text in it. Unfortunately I do not have a sample here, as everything is at my house.Until later

[Guest jacosmit]

Hi Holger and everyoneI managed to read the files using Global Mapper, then export it to a USGS DEM. I renamed the .ort extensions to .txt. Quite nice to see the results finally. Thanx for the help with this.Now, isn't there a batch utility where I can convert XYZ UTM files to a format compatible with popular FS mesh creation utilities and what utilities are available. UP to now I used to convert Dted data to FSTerrain (http://www.mnwright.btinternet.co.uk/) projects and then compile the BGL files.I believe the inf file that needs to be created should be in Arc second format, I'm not sure if the metric system is used by the inf file.Another question, my data also include Mod Clarke data in a .dat and a corosponding .hef (text) file. Althought at much lower resolution (400m, 200m and 50m), how do I read these files. Global Mapper nor MicroDem seems to want to import it. I can open the .dat file, there is a whole lot of text in it. Unfortunately I do not have a sample here, as everything is at my house.Until later

[Guest jacosmit]

I have imported a XYZ file using UTM and WGS84, but instead of placing it close to the coords 28S 22E it places it somewhere close to S60 E16. Could I do anything to better it, or what other datum could be used.

[Holger 0]

Hi Jaco:sorry, no further suggestions other than perhaps you checking common topographic maps of SA and their projections. Might give you some ideas.I can't help but noticing that you twice "dodged" my questions about supporting information. Once more: if you purchase digital elevation data you are entitled to full information about its data format and projection. If you didn't purchase them you could put yourself into a dangerous position by redistributing them online, freeware or payware.Cheers, Holger

[Guest jacosmit]

Hi HolgerI got an answer from them finally.It seems that yes, it is UTM, but uses southing and westing, insead of northing an easting (explains why the cape pinensula is on it's head) and the format should be YXZ and not XYZ, but when importing it as YXZ the coordinates is out of range, acording to Global Mapper.I have to one of the following, create a pluginn for MicroDem or Global Mapper that simulates southing and westing or physically go in to each text file and minus about 5000 lines in 4200 plus files.Any ideas...?On the distribution. The digital data was free, I had to pay the postage but their lincense agreement states that I will have to apply to sell and /or distribute the data.

[Guest jacosmit]

Before I forget. South Africa uses a datum called Hartebeeshoek94, which is entirely based on the WGS84 datum.For more info http://w3sli.wcape.gov.za/SURVEYS/MAPPING/wgs84.htmCheersJaco

[Holger 0]

Hi Jaco:"I have to one of the following, create a pluginn for MicroDem or Global Mapper that simulates southing and westing or physically go in to each text file and minus about 5000 lines in 4200 plus files."Ouch! No wonder you get those data for free ;-)I don't own the full version of GM so can't tell you if/how plugins are created. I'm sure most professional GISs (not sure if I'd count GM among them) would provide translators or macros for even the "stranger" file formats; I know Idrisi and ArcView do. Perhaps post your problem in either the Microdem or the GM support forum?Alternatively, I'd check through websites of the SA government and universities for GIS pages; sometimes you can find free translators or macros or at least helpful advice. Other than that, I'd try doing the necessary adjustments (in EXCEL) to find out whether there is a low-tech way of getting the files to work.Sorry, no ready-to-use help here ;-)Cheers, Holger

[Guest jacosmit]

Ok, I've figured it out by searching the web some more. The data is actually not UTM but Tranverse Mercator in metric format, and I have to multiply both the X and Y with -1, to get it to a Southing / Westing format. Unfortunatly was up till 1:40am this morning and did not take a screenshot. The Cape penensula is lining up properly.Now, more questions:1) How can I get USGS Dems to a format usable by what mesh creation utility.2)Can I convert a USGS DEM to HGT format? How would I go about it.Thanx for the help so far...

[Guest jacosmit]

Here is some screenies...ONe is Dted data downloaded from Nima, the other (hi res) is the SA Surveys & Mapping. If you look north of Table mountain, you will see that even Cape Town Harbour's piers have been detected.

[Holger 0]

Hi Jaco:nice images! Table Mountain looks surprisingly sharp-ridged but that might be an artefact of the mesh display. Also, I rember from a hike up there that it's much less flat than the view from the city would suggest ;-)MicroDEM - http://www.usna.edu/Users/oceano/pguth/website/microdem.htm - reads USGS and NIMA data (the military crowd is the main "customer" for MicroDEM) and the newer versions let you save as 16-bit BSQ, which is a format MS resample.exe can deal with. The necessary parameters for the .inf file can be taken from "Analyze > Header" and "Calculate > Map window corners", respectively.Cheers, Holger

[Guest jacosmit]

Hi HolgerI can't seen to grasp MicroDem's features.I created BSQ with GM, changing the projection to a lat & long (decimal) display format.I then take the info supplied by the header file and created a inf from it. If I run the inf with the usesourcedimensions=1 option, I get a "-9999 found" error, and with usesourcedimensions=0 I cannot seem to find the fruit of my labour in FS.I must say LOD11 runs forever.A compiled BGL is around 5 - 8Mb, depending on using LOD 11 or 12.