Thanks James,
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?
I know my Garmin way-point data is good because it overlays on my Ortho
almost perfectly as a separate layer.
Mike K
On 2/3/2014 8:28 PM, James Wood wrote:
Mike,
Here is a good tutorial overview of the georeferencing tool in QGIS:
http://qgis.spatialthoughts.com/2012/02/tutorial-georeferencing-topo-sheets.html
If the image is not in coordinate space, it will not line up with your
other data. so this operation will be necessary.
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 http://www.gimp.org/.
Best Regards,
James
------------------------------------------------------------------------
Date: Mon, 3 Feb 2014 19:59:14 -0500
From: [email protected]
To: [email protected]; [email protected]
CC: [email protected]
Subject: Re: [Qgis-user] How do I register a Google Map?
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.
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.
My desire is the _digitize_ 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.
Is it hopeless?
Mike K
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