China DCW Data

[Peled]

Does anybody succedded to get the Dcw files for China working ?
i remember that China dcw data were problematic , non of it e00. files are working .
i am interested in making a TaiwanTheatre, but needs a working data for China .
if anybody have any clue how to or from where to get them working , pls PM me or make a reply .

Thanks

Peled.

[Sherlock]

Peled,
did you try it?

[Peled]

Sure------it doesn't work , never mind , i got it now , thanks .

[Sherlock]

How did you get it?

[Peled]

NOT Sure about , but when i tried to get it on a PC In Moscow i Could'nt get it to work with TerrainView or Dem2terrain , now in Israel it works....
So...i guess the ones in the DCW Link are working fine....try it and tell me...

[87th_striker]

Talk to Zaggy. He fixed it a year ago or so. He also did the russian data. There might even be a BAzT version around. The data was fixed with software from SAFE, (FME) http://www.safe.com/

[Peled]

Thanks for the Information Striker !
i will contact Zaggy .

[87th_striker]

From my correspondance with Zaggy. (Hope it's ok, Zags)

http://www.maproom.psu.edu/dcw/faq/ques4.html
What is the datum used in the DCW?

Answer:
Determining the datum for DCW has, unfortunately, not been an easy task. As far as we can determine, it is not mentioned in the documentation that came with the CDs.

The data originally came from ONC (Operational Navigational Charts) put out by the Defence Mapping Agency at a 1:1,000,000 scale. Looking on ONC G-21, of the mid Atlantic Seaboard, one finds that according to this document:
Entire UTM Grid falls within Geodetic Reference System 1980 Ellipsoid There also appear to be charts where the ellipsoid changes at a particular longitude line.

However, according to
http://www.kgs.ukans.edu/software/Wheat ... dcw1qd.htm

For standard and partial quadrangles, coordinate data are in the geographic angular system in decimal degrees (longitude-latitude). The horizontal datum is the World Geodetic System 1984 (WGR84). Feature locations are accurate to approximately 2 kilometers. As stated on the DMA's web site:

Features: The absolute horizontal accuracy of the DCW for all features derived from Operational Navigation Charts (ONCs) is 2040 meters (6700 feet) rounded to the nearest 5 meters at 90% Circular Error (CE), World Geodetic System (WGS84). The accuracy of spot elevations collected from ONC source is 30 meters (100 feet). The accuracy requirements do not apply to feature symbols that are displaced as identified in MIL-STD-600001.

For spliced regions, coordinates will usually be in Universal Transverse Mercator coordinates in meters, with the zone number being that of the central part of the region if the region does not fit into one zone: the table ztblWHEAT_LOG will contain notes on any coordinate transformations.
Recommendation: It should be noted that the difference between the possible datum values is relatively insignificant when compared to the potential error induced simply by the scale of the
data and other sources of error.

There you go, Zaggy Try WGS84, and let me know your progress. I remember that DELETED, the guy that wanted to dictate the usage of his data conversion, had some problems with zero's in the result file. Keep an eye on stuff like that.

Do you guys use Matlab for Bazt ? If so you probably could also write a little code piece to convert it, using the formula from Lambert conversion. I've seen it out there one time, but it's pretty advanced.

If you convert the data, I think you should publish it.... In time. Maybe even Nekromantix, too ? (As a little tribute to Snakeman)

Anyway, send me the result files if you have problems. I'll take a look at them.

Regards,


Striker

-FROM ZAGGY

Gday again Striker...

One quick question regarding conversion with FME... Im to the point of deciding what 'Co-ordinate System' i need to translate to. Ive gone thru the (MASSIVE) list looking for either 'Geographic' or 'Mercator', and found NUMEROUS co-ordinate systems. so i thought id save my self a little bit of work at least, and simply ASK u. Which co-ordinate system will work?

Thanks Ola...

Zaggs



> Yes, russian data are available, but I guess you also want them converted ?
> You can get the data from the link at Nekromantix
> http://www.maproom.psu.edu/dcw/ , then you can convert them using FMW
> http://www.safe.com Trials are free.

[Zaggy]

Does anybody succedded to get the Dcw files for China working ?
i remember that China dcw data were problematic , non of it e00. files are working .
i am interested in making a TaiwanTheatre, but needs a working data for China .
if anybody have any clue how to or from where to get them working , pls PM me or make a reply .

Thanks

Peled.

Sorry, Ive been back round here a few months and was only JUST made aware of this thread... Lets see if i can still help...

China Data:
http://www.simmersworld.com/~openskin/d ... /China.zip (15.3Mb)

If you have any hassles gettingt it, let me know...

[Zaggy]

In addition, some background on the datasets...

The Russian and Chinese Datasets are BIG. Very big, in comparision to the rest of the world.

While the REST of the world's data was rendered to a GEOGRAPHIC (or Mercator) project, for some reason, these BIG datasets were Rendered to a LAMBERT projection ona Clarke1866 Spheriod... You can actually determine quite easily, what project an e00 uses... Load the file into a text editor, and search for the 'PRJ' entry (e00's are divided into sections by a number of three letter Markers, ARC, LOG, PRJ, TOL, IFO are a few), which will tell you what projection you e00 is in. This section is typically in the middle somewhere of the file...

Code: Select all

PRJ  2
Projection    LAMBERT
~
Zunits        NO
~
Units         METERS
~
Spheroid      CLARKE1866
~
Xshift        0.0000000000
~
Yshift        0.0000000000
~
Parameters
~
 70  0  0.000 /* 1st standard parallel
~
 50  0  0.000 /* 2nd standard parallel
~
 110  0  0.000 /* central meridian
~
 0  0  0.000 /* latitude of projection's origin
~
0.00000 /* false easting (meters)
~
0.00000 /* false northing (meters)
~
EOP

Anyway, our F4 terrain tools are a little unforgiving in regards to the structure of the e00's... Firstly, the MUST be projected GEOGRAPHIC, the filename header (first line of the file) MUST be intact (that was a curly one... caught me out for a while, BUT its used to determine the data content of the file!) and the label data MUST be in a specific format for the point data.

But once you sort those things out, its all cool!

FME, back when i first played with this stuff in 2004(?) handled the reprojection VERY well (tho brought my machine at the time, to its KNEES... Throw LOTS of memory at this stuff!), but the ordering of the Label data required a small app (in VB) to be written to extract and reorder the label data... Then of course, the odd little manual fix...

It all doesnt matter now tho, as the data is sorted and out there!

China:
http://www.simmersworld.com/~openskin/d ... /China.zip

Russia:
http://www.simmersworld.com/~openskin/d ... tralv2.zip
http://www.simmersworld.com/~openskin/d ... iaEast.zip
http://www.simmersworld.com/~openskin/d ... iaWest.zip



Zaggs

[Snake Man]

Am I completely out of my mind, but to me, there is no problem using the China data straight from the DCW site with Dem2Terrain v1.9?

[Zaggy]

I think youre completely out of your mind... hahhaha...

But yeah, MANY years ago, when i first started playing with Terrain, my first experiments were on a Taiwain theater (before i was told to STOP, blah blah...)... The First series of China data I got, were projected...

The last time I DL'd the China Data (when i was playing with converting the data), it was STILL Projected, hence why i converted it... FME would have told me if i was converting the data to its current format!

What seems to have happened is, the DCW data for china has been re-projected or updated. It was always one of the most high demand datasets coming off DCW; makes sense it should have been converted to the most convienient format to initially use. I just wish they'd done it to the Russian Data YEARS ago!

Its always the way tho. Blueprint spent 9-12 months on FIXING the SRTM v1 data (removing the ocean 'noise', patching voids and removing spikes), only to have NASA release SRTM v2 shortly there after... (But Bluey's data is actually STILL Better Quality than the NASA released stuff. I dunno how, but NASA screwed it up! The v2 data STILL has voids and Spikes!)...

The important thing is, we have working China data...