anything
AirNav RadarBox
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
 


Author Topic: Satellite imagery adrift  (Read 9055 times)

0 Members and 1 Guest are viewing this topic.

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Satellite imagery adrift
« on: September 12, 2008, 04:34:55 PM »
I've just noticed that the satellite imagery has drifted out of synch with the coastline by a significant amount.  Is there a setting which I may have inadvertently changed, does anyone know?

DC
Go around, I say again go around...

Allocator

  • RadarBox24.com Beta Testers
  • Hero Member
  • *
  • Posts: 3568
Re: Satellite imagery adrift
« Reply #1 on: September 12, 2008, 04:58:00 PM »
I think that you will find the satellite picture is correct and the coastline is just an approximation.  I know that tarbat uses the high definition outline produced by bones for the SBS-1.  I just switch off the Country Boundaries option when I'm using the satellite layer.

AirNav Development

  • AirNav Systems
  • Hero Member
  • *****
  • Posts: 2545
    • AirNav Systems
Re: Satellite imagery adrift
« Reply #2 on: September 12, 2008, 08:35:55 PM »
Allocator is right: if there is any inconsistency between the satellite photo and the boundary lines then the satellite photo is correct. We also switch off boundary lines when sat photos are being shown.

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Re: Satellite imagery adrift
« Reply #3 on: September 12, 2008, 09:06:54 PM »
Fair enough.  Didn't notice the discrepancy before.

DC
Go around, I say again go around...

testmonkey

  • Full Member
  • ***
  • Posts: 127
Re: Satellite imagery adrift
« Reply #4 on: September 12, 2008, 10:49:15 PM »
Fair enough.  Didn't notice the discrepancy before.

Try looking at Malta or other similar sized land masses. Doesn't even exist according to the boundary lines :)
testmonkey
--------------------------------------------
RB - MVT9000 - UBC30XLT (for acars)

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Re: Satellite imagery adrift
« Reply #5 on: September 14, 2008, 02:52:59 PM »
Can't seem to find the Country Boundaries option to switch off...  someone point me in the right direction, ta.

DC
Go around, I say again go around...

RodBearden

  • Hero Member
  • *****
  • Posts: 8639
    • Rod's RadarBox Downloads
Re: Satellite imagery adrift
« Reply #6 on: September 14, 2008, 03:01:45 PM »
Hi DC

Its in the Gereral Signs drop-down (next to the Home button).

Rod
Rod

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Re: Satellite imagery adrift
« Reply #7 on: September 14, 2008, 03:07:29 PM »
Airnav, and those interested.  I've been doing a little checking on the idea that the satellite map is more accurate than the outline.

Using a path profiler, I am finding that the satellite image is consistently wrong, and that the outline is more accurate, which is contrary to your assertion.

Simply by checking the same position on the path profiler against the identical point on both the outline and satellite image in RadarBox, the discrepancy is quite considerable in places.  (I am comparing points on the coast in the south of France - Sete, for instance).

In case I'm doing it wrong, try it for yourselves.  I'd be interested in any comments.  If I'm in error, I'll get me coat...

DC
Go around, I say again go around...

Allocator

  • RadarBox24.com Beta Testers
  • Hero Member
  • *
  • Posts: 3568
Re: Satellite imagery adrift
« Reply #8 on: September 14, 2008, 03:11:31 PM »
DC,

Is this consistent, or is it at the edges of the layer?  It all looks OK to me at the centre when I'm watched aircraft take off and land.  Maybe it's an expansion thing?

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Re: Satellite imagery adrift
« Reply #9 on: September 14, 2008, 03:30:26 PM »
Take at look at the attached pic.  Most of the coastline is out of synch.  I've not zoomed or done anything, and the map is a spherical projection.

DC
« Last Edit: September 14, 2008, 03:41:21 PM by Deadcalm »
Go around, I say again go around...

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Re: Satellite imagery adrift
« Reply #10 on: September 14, 2008, 03:51:29 PM »
Oh, and thanks, Rod!

DC
Go around, I say again go around...

RodBearden

  • Hero Member
  • *****
  • Posts: 8639
    • Rod's RadarBox Downloads
Re: Satellite imagery adrift
« Reply #11 on: September 14, 2008, 06:27:16 PM »
Maybe you just answered the question yourself, DC.

Perhaps the satellite images are only accurate with Mercator projection? They seem more accurate for me with that. Perhaps they are pre-corrected for Mercator?

Rod
Rod

Deadcalm

  • Sr. Member
  • ****
  • Posts: 381
Re: Satellite imagery adrift
« Reply #12 on: September 15, 2008, 07:39:05 AM »
Hmm... switching to the Mercator projection and reloading the satellite image certainly makes a difference.  Not perfect, but better.  I tend to use the spherical projection as a matter of course.

Maybe it would be an idea if Airnav were to add the proviso somewhere, that satellite imagery is only successful with the Mercator projection.

I won't be getting me coat on this occasion - just me hat!!

DC
Go around, I say again go around...