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

[Jeff Ngwane]

Thank you very much for responses.



I am ok with the output because I use raster georeferencing for display
purposes and will be done in conjunction with latest satellite image.
Actually, I got GCPs from Google Earth image. The problem is when
georeferenced image get loaded up on QGIS it does not align with cadastre.
I do not have a problem with topographic maps as they do align; same
applies to satellite images with map projection (old and new). My main
challenge is with historical aerial photo maps from NGI. I only received
images (jpeg) and flight plans from NGI with no .tfw file and struggling.



With Thanks


Jeff

On 17 November 2016 at 08:47, Aslam Parker <Aslam.Parker at drdlr.gov.za>
wrote:

> 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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