[OSGeo Africa] Georeferencing or overlaying old aerial photograph with cadastre

[Aslam Parker]

Hi 

Please let me clarify :)

NGI standard orthorectification is a rigorous process that uses high resolution aerial imagery, post processed external orientation parameters, precise camera models, photo ground control, rigorous bundle block adjustment, digital elevation models and individual orthorectification, mosaicking, colour balancing and cutting into tiles, and finally compression.

When I said we do it all the time, I was referring to numerous requests for add-hoc georeferencing of our historical imagery, especially for land restitution. As you are aware, our digital orthorimagery only dates back to 1990's but we have historical aerial imagery dating back to 1926. In this case we often use the rubber sheeting method, but are aware of its limitations. We are looking into software that is specifically suited for orthorectification of historical imagery using DEM and patch rectification.

I trust that this clarifies matters.


-----Original Message-----
From: Africa [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Chris
Sent: 17 November 2016 07:20 AM
To: Africa local chapter discussions
Subject: Re: [OSGeo Africa] Georeferencing or overlaying old aerial photograph with cadastre


    Morning Aslam ,

    Georeferencing by common points

    I believe you guys ( NGI / SG )  have a more advanced way of doing this 
    whereby one ends up with a proper accurate geo-refeerenced orthophoto 
    ( orthorectified )

    I am curious ?

    CM



On 16 Nov 2016 at 11:06, Aslam Parker wrote:

> Hi Jeff
 
> My colleague Muhammed Deal <Muhammed.Deal at drdlr.gov.za> has a tutorial 
> that he can send you, we do this all the time on QGIS.
 
> Please take note that if you do a georeferencing by common points, 
> this amounts to  rubbersheet/transformation and does not create an 
> orthorectified imagery and the georeferencing will be approximate.


 
> From: Africa [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Jeff 
> Ngwane Sent: 16 November 2016 12:17 PM To: Africa local chapter 
> discussions Subject: [OSGeo Africa] Georeferencing or overlaying old 
> aerial photograph with cadastre
 
> Hi,
 
> How to correctly georeference old aerial photograph (i.e 1972) for 
> purpose of being aligned with up to date cadastre on QGIS recent 
> versions? I have been trying but in vain. Please help me.
 
> Thank
 
> Jeff


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