[Geo4All] Need help -- Unsupervised classification in QGIS of a non-georeferenced aerial photo?

[Charlie Schweik]

Thanks tons Lene! And also I'm grateful to Nikos and Adam Steer for ideas
as well.
This will be one of a set of labs for an Unmanned Aerial Systems lab manual
I am developing and will share with the GeoForAll community when finished.

This is a simple 1-image RGB analysis lab counting gull populations on a
reservoir, trying to get population #s as the water agency folks don't have
a good idea how many and they make messes in the water supply!

Thanks again everyone!
Charlie Schweik


On Sat, Feb 23, 2019 at 4:24 PM Lene Fischer <lfi at ign.ku.dk> wrote:

> Hi
>
> I made this workflow – a bit out of the original question – but found it
> fun to do  - (Like Saturday eve jigsaw puzzle)
>
>
>
> How to count seagulls.
>
>
>
> Workflow:
>
>
>
> Open some sort of background – eg. OSM – Remember to have your CRS correct
>
> Add your images to a folder
>
> Use plugin Import Photos. This gives you the position of the image.
>
>
>
> I estimated the area for the photo – Used the measure line for the ‘setup’.
>
> Georeferenced the 4 corners and added the images (Raster>georeference)
>
>
>
> Create a temp scratch layer as a mask for the area with seagulls.
>
> Clip raster by mask layer
>
>
>
> Change the image symbology from rgb to singleband grey
>
> In Rasctercalculator find rasterband at 1>=130 change col and row with
> divide by 4 – if I use original pixelsize the next step will have too many
> polygons.
>
>
>
> Rasterpixel to polygon or polygonise
>
>
>
> Select Expression find field ‘Value’ or DN = 0 (depends which finction you
> use for raster to polygons).  Delete selected
>
> Buffer 0.01 Dissolve
>
> Multipart to single part
>
> Find features smaller than a seagullà delete
>
> Find larger polygons (eg. Plastic)
>
> Count polygons
>
>
>
> In your image 463 seaguls.
>
> Happy counting. In this way your student learn to manually do the tricks –
> and might do it in Modelbuilder too ;-)
>
>
>
>
>
>
>
> [image: cid:image005.png at 01D4CBC4.6947D1D0]
>
>
>
> Regards
>
>
>
> *Lene Fischer*
>
> Associate Professor
>
>
>
> *University of Copenhagen*
>
> Department of Geoscience and Natural Resource Management
>
> Forest and Landscape College
>
> Nødebovej 77a
>
> 3480 Fredensborg
>
> Denmark
>
>
>
>
>
> MOB +45 40115084
>
> *lfi at ign.ku.dk* <lfi at ign.ku.dk>
>
>
>
>
>
>
>
>
>
> <http://@Lene_Fischer>
>
>
>
>
>
>
>
> *Fra:* GeoForAll [mailto:geoforall-bounces at lists.osgeo.org] *På vegne af *Charlie
> Schweik
> *Sendt:* 23. februar 2019 13:52
> *Til:* OsGeo, GeoForAll
> *Emne:* [Geo4All] Need help -- Unsupervised classification in QGIS of a
> non-georeferenced aerial photo?
>
>
>
> Hi GeoForAll colleagues,
>
>
>
> I'm trying to generate an unsupervised classifcation of a single aerial
> photo taken by a quadcopter of gulls in a water body. I'm trying to count
> the gulls.
>
> The image is in X/Y Cartesian coordinates -- it is not georeferenced. I'm
> trying to use QGIS' Semi-automated classification plug-in.
>
> I can't get it to work because the image isn't in a geographic or
> projected coordinate system.
>
>
>
> Does anyone have any ideas on how I could do this in QGIS?
>
>
>
> Thanks in advance,
>
>
>
> Charlie Schweik
>
>
>
>
> --
>
> Charlie Schweik
>
> Professor
>
> Department of Environmental Conservation & School of Public Policy
>
> University of Massachusetts, Amherst
>
>
>
> Facebook: Charles.Schweik
>
> Twitter: @cschweik
>
>
>


-- 
Charlie Schweik

Professor
Department of Environmental Conservation & School of Public Policy
University of Massachusetts, Amherst

Facebook: Charles.Schweik
Twitter: @cschweik
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/geoforall/attachments/20190223/7d054f5e/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 750454 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/geoforall/attachments/20190223/7d054f5e/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.gif
Type: image/gif
Size: 4971 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/geoforall/attachments/20190223/7d054f5e/attachment.gif>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image003.png
Type: image/png
Size: 1280 bytes
Desc: not available
URL: <http://lists.osgeo.org/pipermail/geoforall/attachments/20190223/7d054f5e/attachment-0001.png>