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Google Earth Coverage of New Zealand

Show Profile  Michael Posted: 23 July 2009, 3:07 PM  
Yes the 3 years old thing they say needs a large grain of salt, Lower Hutt appears to be 6-7 years old and there's a low-res block in the middle of the valley where you can't see a thing. Still it must be a huge task arranging cover for the entire world, and I guess its good that the military-aerospace industry is uninterested in us...

Show Profile  The Map Guy Posted: 23 July 2009, 6:05 PM  
The strip between Kinloch and Tokoroa is unusable - don't know if this is 3 years old or 30. Can't see anything that is useable (which is distressing). You'd think Google Earth people would have something to cover two large towns - I can understand areas which have next to no people being at the bottom of the list for priority.

The term "low" for resolution is rather relative. Most of NZ is low resolution which we may consider high resolution (i.e. down to 100m) compared with Edinburgh in Scotland which has a resolution down to around 40m. Images which have a resolution of kilometres are useless and are unuseable.

Show Profile  Michael Posted: 27 August 2009, 9:04 PM  
Hi-resolution Mar 2009 photography for the residential parts of Wellington. First time I've seen photos patched in on a non-rectangular basis. Be interesting to check alignment across the joins.

Show Profile  addison Posted: 3 October 2009, 3:55 PM  
I have heard that there is software (other than US$400 a year Google Earth Pro) that you can define an area and it will automatically stitch together the higher resolution images for you.

Has anyone heard of this? Anyone used it successfully? Let us know what you have used!

Show Profile  The Map Guy Posted: 3 October 2009, 11:01 PM  
I'd love to know of some software that would automatically do this laborious task. I have manually stitched around 8 hi-res. screen shots together - worked OK, but took a while to do it.

Show Profile  Michael Posted: 4 October 2009, 10:00 AM  
I'm curious about what you get when you stitch together images that contain distortion?

Show Profile  The Map Guy Posted: 4 October 2009, 12:11 PM  
Don't know. I must have been lucky with the area I did as it had next to no distortion. Managed to download images with the same scale factor - not always easy to do. Maybe next time I try I will not be able to reproduce the same sort of results.

I suppose you may have to capture small areas to stitch together if you are aware of distortion.

Show Profile  mark Posted: 4 October 2009, 2:42 PM  
I use a perspective transformation matrix for stitching together distorted images at work.

Show Profile  The Map Guy Posted: 4 October 2009, 7:18 PM  
Could you convert that into plain English please. How can other people also do it?

Show Profile  addison Posted: 6 October 2009, 9:06 PM  
I have found some good software, which is relatively cheap to do what we want it to do. It is called GMID - Google Satellite Maps Downloader.

You define the longitute/latitude of the two alternate corners and the zoom factor and it will download the series of images for you. You can then get it to join them all together to form one big image.

There are restrictions on it, as if you download a heap of images in a short period of time Google realises you aren't doing it for 'recreational' purposes - so can temporarily block your IP. Not to fear, can just wait it out for 20-30mins or alternatively you just do a smaller section at a time (eg a suburb).

I left my computer on today trying to do all of Hamilton, came home to find 19gigs of google earth images in the folder and it still hadn't finished. I think I was trying for a zoom which was too high!

Show Profile  Michael Posted: 7 October 2009, 10:43 AM  
I believe that Google Earth images are not corrected for height-related (and possibly other) distortions, and the assembly into a supposedly seamless earth has flaws. For example Dowse Drive in Lower Hutt suddenly moves sideways by the size of a typical domestic section. I have found other overlaps and underlaps.

While it is tempting to stitch together zoomed in images to produce a single image to use as a background in OCAD, I prefer to (a) establish a trustworthy framework eg from orthophotos and (b) fit small Google Earth images to that framework ONE BY ONE. On steep land there will generally be a mismatch at the overlaps (this is evidence of the distortion) but it should keep the distortions within bounds.

There is a suggestion that Google Earth Pro (not free) accesses better photography without some of these flaws. I would think the task of maintaining worldwide coverage is hard enough without having two sets, but I would be interested if anyone can comment?

Show Profile  fraser Posted: 7 October 2009, 11:00 AM  
Simon, you can use your google earth images and combine it with Hamilton at 0.5m contours and make a great O map.

Show Profile  Greg Posted: 7 October 2009, 11:23 AM  
Michael, ask Chris Forne, I believe he is doing something about that for fun (and to map all of the Port Hills)

Show Profile  Michael Posted: 2 November 2009, 8:25 PM  
Cuttance Block (SI Champs) has very new photography (July 09) but there are very long shadows. First time I've seen it this bad.

Latest GE newsletter refers to new photography for NZ but doesn't say where. Anyone know?

Show Profile  Michael Posted: 1 December 2009, 7:19 PM  
New imagery for Tauranga, looks good.

New imagery for the bad patch in Lower Hutt, only slightly less bad. You can make out the streets now.

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