I agree, I have been having A LOT of difficulty with people submitting maps
with only 3 registration points and have had abysmal results. They don't
seem to understand when I ask for more. I would even suggest a minimum of
5. One for each corner and one smack dab in the middle. One guy I
mentioned this to submitted a map with 12! It was a bit of extra work but
it registered like a dream. Well, at least as dreamy as image registration
can get.
-Ben
> -----Original Message-----
> From: Mats Elfström [SMTP:[EMAIL PROTECTED]]
> Sent: Monday, September 20, 1999 11:24 PM
> To: Dyan Catamaran
> Cc: [EMAIL PROTECTED]
> Subject: Re: MI batching register
>
> Dyan Catamaran wrote:
> > I would like to register several (200) images on a base map. The base
> map
> > can be one map or two hundred maps. There are three GPS control points
> > per image. The manual process seems to be lengthy and costly. I wonder
> > if you know any automatic process to register images. I foresee a kind
> of
> > application where the image and base map filenames can associated by a
> > common link and a routine / batch would be able to do the job. Any
> ideas?
>
> Hi Dyan!
> Assuming that you have all image file names and their corresponding
> control points (pixel values/coordinates) in a computer readable list,
> you can do like this:
> 1 Register one image manually
> 2 Check the syntas in the resulting TAB file
> 3 Write a program that writes such TAB files for all of the images,
> reading data from the list
>
> Another thing is the highly questionable value of a georeference with
> only 3 points.
> You must realize that three points is the absolute minimum for
> georeferencing, and that you will always get a 0 pixel error, no matter
> what errors may exist in the control points.
> I would say that 4 points is the minimum number of control points.
> (Unless we are talking about ortho photos in which case the provider
> ought to have provided the necessary TAB files in the first place.)
>
> Regards, Mats.E
> --
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