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<div class="moz-cite-prefix">So I work with Forestry guys and we do
some very similar things when georeferencing. You need a good
point spacing - and typically I describe that as a point at each
coner of the image you are going to georeference plus one for the
middle or (sorry for using this example but they have really good
docs) -
<a class="moz-txt-link-freetext" href="http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Georeferencing_a_raster_dataset">http://webhelp.esri.com/arcgisdesktop/9.2/index.cfm?TopicName=Georeferencing_a_raster_dataset</a>
<br>
<br>
If it were me I would do this: <br>
1. go to USDA Datagateway - <a class="moz-txt-link-freetext" href="http://datagateway.nrcs.usda.gov/">http://datagateway.nrcs.usda.gov/</a> -
and download a NAIP image of your Area (sorted by county). It will
be sid format (probably) - so if you are on windows you should be
OK for opening up the image. <br>
2. Use that to georeference the Google earth Screenshot. It will
give you a lot more control points than just your GPS. <br>
<ul>
<li>GPS can be notorious for not quite being right if you didn't
way point average - my forestry guys GPS property corners and
that makes me not happy every time they do it.</li>
<li>Both Google and Bing are good and the open layers plugin
rocks - but - both image layers aren't captured (at least to
me) with mapping in mind - i.e. they may be questionable. <br>
</li>
</ul>
<br>
OR <br>
<br>
1. Download the GPX data from your unit using either QGIS or DNR
GPS <br>
2. Convert to shapefile. <br>
3. Create your contours there using a new shapefile (digitize them
in again). <br>
<br>
I know I just glassed over a ton of technical by doing a 1 2 3
type scenario but I think (just my opinion) there's more hair
pulling than you need to be experiencing (For the record I'm bald
so I know all about hair pulling). <br>
<br>
Yell if you need more help either off list or on list - I hope
some of this at least pushes you in a good direction. <br>
<br>
Randy<br>
<br>
<br>
<br>
<pre class="moz-signature" cols="72">-----------------
Randal Hale, GISP
North River Geographic Systems, Inc
<a class="moz-txt-link-freetext" href="http://www.northrivergeographic.com">http://www.northrivergeographic.com</a>
423.653.3611 <a class="moz-txt-link-abbreviated" href="mailto:rjhale@northrivergeographic.com">rjhale@northrivergeographic.com</a>
<a class="moz-txt-link-rfc2396E" href="mailto:rjhale@northrivergeographic.com"><mailto:rjhale@northrivergeographic.com></a>
twitter:rjhale
<a class="moz-txt-link-freetext" href="http://about.me/rjhale">http://about.me/rjhale</a></pre>
On 02/05/2014 12:04 PM, Mike Keelan wrote:<br>
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<div class="moz-cite-prefix">Thanks James,<br>
<br>
I got through the geo-referencing operation and it did generate
a new modified layer based on my .jpg. However the new layer is
badly distorted/stretched, (I used 4 coordinate Garmin GPS
reference points), and it is not in the right location. I can
only find it by zooming to that layer extent. I'm wondering if
my coordinate data from my Garmin is consistent with what the
geo-referencing program uses? My Garmin data is xx.xxxxxx and
it uses negative numbers to represent East instead of West. Or,
might there be an accuracy issue?<br>
<br>
I know my Garmin way-point data is good because it overlays on
my Ortho almost perfectly as a separate layer.<br>
<div class="moz-signature"><br>
Mike K<br>
<br>
</div>
On 2/3/2014 8:28 PM, James Wood wrote:<br>
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<div dir="ltr">Mike,<br>
Here is a good tutorial overview of the georeferencing tool
in QGIS:<br>
<a moz-do-not-send="true"
href="http://qgis.spatialthoughts.com/2012/02/tutorial-georeferencing-topo-sheets.html">http://qgis.spatialthoughts.com/2012/02/tutorial-georeferencing-topo-sheets.html</a><br>
<br>
If the image is not in coordinate space, it will not line up
with your other data. so this operation will be necessary.<br>
<br>
Also, just as a side, I would think that an export from
Powerpoint would degrade image quality (depending on the
original). I would look at and maybe try for future use The
Gimp (which is an open source, free Photoshop-type
application). It will give you more control on export of not
only various output formats but also pixel and color depth,
and the like. The official site is <a moz-do-not-send="true"
href="http://www.gimp.org/">http://www.gimp.org/</a>.<br>
<br>
Best Regards,<br>
James<br>
<br>
<br>
<div>
<hr id="stopSpelling">Date: Mon, 3 Feb 2014 19:59:14 -0500<br>
From: <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:tmike.elhoa@comcast.net">tmike.elhoa@comcast.net</a><br>
To: <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:tech@wildintellect.com">tech@wildintellect.com</a>;
<a moz-do-not-send="true" class="moz-txt-link-abbreviated"
href="mailto:etourigny.dev@gmail.com">etourigny.dev@gmail.com</a><br>
CC: <a moz-do-not-send="true"
class="moz-txt-link-abbreviated"
href="mailto:qgis-user@lists.osgeo.org">qgis-user@lists.osgeo.org</a><br>
Subject: Re: [Qgis-user] How do I register a Google Map?<br>
<br>
<div class="ecxmoz-cite-prefix">OK, I installed the Open
Layers plugin and it works very nice but it won't do what
I need, so let me be more specific and see if there might
be a remedy. <br>
<br>
The contour lines that I want were actually obtained using
a hand held Garman GPS. The Garman data was overlaid on
the Google map, (with water depths), special
integration, then that map was exported as a Jpeg, then
imported to PowerPoint where a visual interpolation was
done to make the final set of contour lines for the
various lake water depths.<br>
<br>
My desire is the <u>digitize</u> these contour lines as a
set of separate layers. ie 5' deep, 10' deep, etc. There
are many good uses for these layers, but they must be
accurate as to location and size. I don't think I
necessarily need spacial info on the "map"/Jpeg if I can
get the whole map in the right position, and size, so I
can do the digitizing (which would then have the spacial
info). Then I can discard the Jpeg.<br>
<br>
Is it hopeless?<br>
<br>
Mike K<br>
<br>
<br>
<br>
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