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Hi Jeff,<br>
You might want to google "how to orthorectify an aerial photo" so
that you begin to understand the enormity on both the task and the
information needed, for "How to correctly georeference...." an
image.<br>
That is why I asked you the type of terrain (flat or not) in my
first response.<br>
Reading the other responses, and assuming that it is mostly for
visual use, rubber-sheeting is your simplest method - even if
tedious. You're not going to get great results if the terrain is
mountainous.<br>
<br>
Hope you don't have too many images......<br>
<br>
Regards,<br>
Zoltan<br>
<br>
<br>
<div class="moz-cite-prefix">On 2016/11/17 09:56, Jeff Ngwane wrote:<br>
</div>
<blockquote
cite="mid:CANqcA6NZm3+kCNCgyuoRn554PT3qjekZRQuDr8CATGFWs7nJ+Q@mail.gmail.com"
type="cite">
<div dir="ltr">
<p class="MsoNormal"
style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span
style="font-size:7pt;font-family:arial,sans-serif;color:rgb(80,0,80)">Thank
you very much for responses. <span></span></span></p>
<p class="MsoNormal"
style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span
style="font-size:7pt;font-family:arial,sans-serif;color:rgb(80,0,80)"><span> </span></span></p>
<p class="MsoNormal"
style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span
style="font-size:7pt;font-family:arial,sans-serif;color:rgb(80,0,80)">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.
<span></span></span></p>
<p class="MsoNormal"
style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span
style="font-size:7pt;font-family:arial,sans-serif;color:rgb(80,0,80)"><span> </span></span></p>
<p class="MsoNormal"
style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span
style="font-size:7pt;font-family:arial,sans-serif;color:rgb(80,0,80)">With
Thanks <span></span></span></p>
<p class="MsoNormal"
style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span
style="font-size:7pt;font-family:arial,sans-serif;color:rgb(80,0,80)"><span> </span></span></p>
<span
style="font-size:7pt;line-height:115%;font-family:arial,sans-serif;color:rgb(80,0,80)">Jeff</span><br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On 17 November 2016 at 08:47, Aslam
Parker <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:Aslam.Parker@drdlr.gov.za" target="_blank">Aslam.Parker@drdlr.gov.za</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi<br>
<br>
Please let me clarify :)<br>
<br>
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.<br>
<br>
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.<br>
<br>
I trust that this clarifies matters.<br>
<span class="im HOEnZb"><br>
<br>
-----Original Message-----<br>
From: Africa [mailto:<a moz-do-not-send="true"
href="mailto:africa-bounces@lists.osgeo.org">africa-bounces@lists.<wbr>osgeo.org</a>]
On Behalf Of Chris<br>
Sent: 17 November 2016 07:20 AM<br>
To: Africa local chapter discussions<br>
</span>
<div class="HOEnZb">
<div class="h5">Subject: Re: [OSGeo Africa] Georeferencing
or overlaying old aerial photograph with cadastre<br>
<br>
<br>
Morning Aslam ,<br>
<br>
Georeferencing by common points<br>
<br>
I believe you guys ( NGI / SG ) have a more
advanced way of doing this<br>
whereby one ends up with a proper accurate
geo-refeerenced orthophoto<br>
( orthorectified )<br>
<br>
I am curious ?<br>
<br>
CM<br>
<br>
<br>
<br>
On 16 Nov 2016 at 11:06, Aslam Parker wrote:<br>
<br>
> Hi Jeff<br>
<br>
> My colleague Muhammed Deal <<a
moz-do-not-send="true"
href="mailto:Muhammed.Deal@drdlr.gov.za">Muhammed.Deal@drdlr.gov.za</a>>
has a tutorial<br>
> that he can send you, we do this all the time on
QGIS.<br>
<br>
> Please take note that if you do a georeferencing by
common points,<br>
> this amounts to rubbersheet/transformation and
does not create an<br>
> orthorectified imagery and the georeferencing will
be approximate.<br>
<br>
<br>
<br>
> From: Africa [mailto:<a moz-do-not-send="true"
href="mailto:africa-bounces@lists.osgeo.org">africa-bounces@lists.<wbr>osgeo.org</a>]
On Behalf Of Jeff<br>
> Ngwane Sent: 16 November 2016 12:17 PM To: Africa
local chapter<br>
> discussions Subject: [OSGeo Africa] Georeferencing
or overlaying old<br>
> aerial photograph with cadastre<br>
<br>
> Hi,<br>
<br>
> How to correctly georeference old aerial photograph
(i.e 1972) for<br>
> purpose of being aligned with up to date cadastre
on QGIS recent<br>
> versions? I have been trying but in vain. Please
help me.<br>
<br>
> Thank<br>
<br>
> Jeff<br>
<br>
<br>
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</blockquote>
</div>
<br>
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<br>
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<br>
<pre class="moz-signature" cols="72">--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 <a class="moz-txt-link-abbreviated" href="http://www.geograph.co.za">www.geograph.co.za</a>
===========================================</pre>
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