Coastline
Geo- for grown-ups
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages    Log inLog in 
  GamesGames   


Bookmark this site!
Coastline

 
Post new topic   Reply to topic     Forum Index -> SMC contour maps
View previous topic :: View next topic  
Author Message
dick
Member


Joined: 03 Nov 2005
Posts: 18

PostPosted: Thu Dec 29, 2005 4:45 pm    Post subject: Coastline Reply with quote

In the guide and other forum topics it is suggested that the coastline of the contour maps is better than that on the Mapsource. I generally use European Roads and Recreation v 4.00. I happened to check the area near Eastbourne and, at higher levels of detail and zoom have found what appears to be a new promontory rising to 50m or more at N50 45.702, E0 17.655. Is there a reason for such an error?
Back to top
View user's profile Send private message
Wildlifewriter
Founder member


Joined: 04 Aug 2005
Posts: 948
Location: Norn Iron

PostPosted: Thu Dec 29, 2005 5:19 pm    Post subject: Reply with quote

It certainly looks a bit suss...

It's years since I was in Eastbourne - but I remember a pier running out to sea at or around that location. It was a fairly substantial pier, too, with a concert hall or something at the far end.

Could be wrong, of course. Question


-Wlw
_________________
A brussels sprout is for life, not just for Christmas
Back to top
View user's profile Send private message Send e-mail
GSV3MiaC
Member


Joined: 14 Nov 2005
Posts: 12

PostPosted: Thu Mar 09, 2006 10:32 pm    Post subject: Reply with quote

The proposed V2 SMC mapping will/would use the NASA 'Water Body Data' shapefiles, where some poor s*d has drawn around every rock and islet to the 3-arcsec accuracy of the SRTM DEM dataset (and used the ocean level as a mask to zero elevations).

These are MUCH more accurate than even the 'detailed' coast outlines from V1.2, although they do exhibit 'steps' (of 3 arcsec) rather than smooth outlines, if you zoom in far enough. See the sample on the other thread.

Comments over on that thread please. I'll look at Eastbourne separately if someone gives me lat/lon.
Back to top
View user's profile Send private message
dick
Member


Joined: 03 Nov 2005
Posts: 18

PostPosted: Fri Mar 10, 2006 5:48 pm    Post subject: Reply with quote

Lat/lon are as per my initial posting above. I find it shows up when zoom set at 500 ft on my PC.
Back to top
View user's profile Send private message
GSV3MiaC
Member


Joined: 14 Nov 2005
Posts: 12

PostPosted: Fri Mar 10, 2006 6:02 pm    Post subject: Reply with quote

Ah, Ok, I finally twigged you said EAST 0 17' etc. .. Yes, there is an artefact there, caused by voids in the original data and what the Blackart algorithm did to fill them in. That's why you always should review the 'void' data.

I've uploaded a .jpg to

http://www.quik.clara.co.uk/maps/eastb1.jpg

The (proposed) version 2 example (sorry, this is a screen capture from gpsmapedit, the V2 contours are no way ready for mapsource yet) is at

http://www.quik.clara.co.uk/maps/eastb2.jpg

Note that the voids have been patched (by NASA), so the problem has gone away. note the contours are probably more pleasing too. Oh, and you havea real cost.
Back to top
View user's profile Send private message

Display posts from previous:   
Post new topic   Reply to topic     Forum Index -> SMC contour maps All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Create your own free forum now!
Terms of Service Purchase Ad Removal Forum Archive Report Abuse