How accurate is the bottom mapping in DW?

Castout · 03-12-08, 02:35 AM

I asked because I found that most of the north sea is actually very shallow in depth in DW (being less than 50 m/150 feet deep).

Again I'm comparing this with SH3 where as I recalled the north sea in SH3 is generally much deeper than in DW.

Delareon · 03-12-08, 05:05 AM

hm as far as i know is the bottom mapping in dw based on some satelite data.
not sure where i have this information from.....

and if i compare these 2 simulations i would better ask if the bottom mapping in SH is correct.

Dr.Sid · 03-12-08, 05:47 AM

In the file WCDEM.dem you can read:

Merged Gtopo30 and TerrainBase Data, DEM format (STM 2-23-98)

GTopo30 is free dataset, easy to google.

GTopo30 give teoretical resolution about 500m on the equator. DW has it downscaled somehow, I estimate it to 1km above the water, and even less under the water, even to 4km. Their DEM file is quite small. 2km resolution is 116M. Gtopo30 with 500m is about 2G. DW's file is 130M, it will be some kind of mix.

Most of the data in these sets is made by satellites. These give great precision for dry land. Much less for sea bottom, especially in shallow waters. How big the errors are, I can't tell. I have no better data to compare it.

All naval charts are made by much better sonar mapping, but these data are not free, AFAIK.

PS: by resolution I mean grid size. Depth itself is stored in integer meters.

SeaQueen · 03-12-08, 07:03 AM

I'm not sure the issue is so much one of accuracy (it's actually pretty good, in general). The problem is resolution. The problem is particularly bad in shallow and coastal areas, to the point that entire islands are sometimes missing as well as harbors. I remember one time I tried to make a scenario where an ESG sailed into the Gulf of Aden only to find the map had insufficient resolution to accurately portray that part of the world and as a result it wasn't easy to get the ships in and out of the Gulf.

Quote:

Originally Posted by Castout

I asked because I found that most of the north sea is actually very shallow in depth in DW (being less than 50 m/150 feet deep).

Castout · 03-12-08, 05:40 PM

:hmm: Thanks

03-12-08, 02:35 AM	#1
Castout Silent Hunter Join Date: Nov 2006 Location: Jakarta Posts: 4,794 Downloads: 89 Uploads: 6	How accurate is the bottom mapping in DW? I asked because I found that most of the north sea is actually very shallow in depth in DW (being less than 50 m/150 feet deep). Again I'm comparing this with SH3 where as I recalled the north sea in SH3 is generally much deeper than in DW. __________________ My blog: http://exposingsingapore.wordpress.com/

03-12-08, 05:47 AM	#3
Dr.Sid The Old Man Join Date: May 2005 Location: Czech Republic Posts: 1,458 Downloads: 6 Uploads: 0	In the file WCDEM.dem you can read: Merged Gtopo30 and TerrainBase Data, DEM format (STM 2-23-98) GTopo30 is free dataset, easy to google. GTopo30 give teoretical resolution about 500m on the equator. DW has it downscaled somehow, I estimate it to 1km above the water, and even less under the water, even to 4km. Their DEM file is quite small. 2km resolution is 116M. Gtopo30 with 500m is about 2G. DW's file is 130M, it will be some kind of mix. Most of the data in these sets is made by satellites. These give great precision for dry land. Much less for sea bottom, especially in shallow waters. How big the errors are, I can't tell. I have no better data to compare it. All naval charts are made by much better sonar mapping, but these data are not free, AFAIK. PS: by resolution I mean grid size. Depth itself is stored in integer meters. Last edited by Dr.Sid; 03-12-08 at 06:02 AM.

03-12-08, 05:40 PM	#5
Castout Silent Hunter Join Date: Nov 2006 Location: Jakarta Posts: 4,794 Downloads: 89 Uploads: 6	:hmm: Thanks __________________ My blog: http://exposingsingapore.wordpress.com/

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

03-12-08, 05:05 AM	#2
Delareon Planesman Join Date: Dec 2006 Posts: 192 Downloads: 77 Uploads: 0	hm as far as i know is the bottom mapping in dw based on some satelite data. not sure where i have this information from..... and if i compare these 2 simulations i would better ask if the bottom mapping in SH is correct.