Opening Google Earth kmz files in QGIS?

Question

I've build an image overlay in Google Earth, but I want to add some other layers via QGIS. In QGIS 2.18.15 on Windows 10, the kmz files just open by adding a raster layer. But...they're clearly wrong. The information in the doc.kml file appears to be a bounding box and the display in QGIS looks like the aspect ratio is wrong, as if the rotation parameter was completely ignored.

So what's the magic to make this work? I have no idea where to start on this and my Google-fu trying to find an answer has failed me.

-- Additional info

I'm trying to add a couple of images, but they're not showing up...

Here is the Google Earth Overlay. Note that aspect ratio of the image.

Google Earth Overlay

Here's what happens when I load the kml into QGIS:

QGIS KML Load

The aspect ratio is wrong, and I really expected north to still be "up".

-- Edit

The QGIS CRS is EPSG:4326. I think I tried forcing EPSG:3857 based on something I found elsewhere about Google Earth, but there is no visible different. If I add the north arrow to QGIS, it points straight up, aligned with the image. Not that the original map is an orienteering map so the north lines on it are in fact magnetic north. What I was aiming for was to pull it into QGIS after getting it calibrated via Google Earth so I could layer a UTM grid over the map.

Here's the doc.kml extracted from the KMZ file:

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" 
xmlns:gx="http://www.google.com/kml/ext/2.2" 
xmlns:kml="http://www.opengis.net/kml/2.2" 
xmlns:atom="http://www.w3.org/2005/Atom">
<GroundOverlay>
    <name>Untitled Image Overlay</name>
    <color>66ffffff</color>
    <Icon>
        <href>files/CCI_000001.jpg</href>
        <viewBoundScale>0.75</viewBoundScale>
    </Icon>
    <LatLonBox>
        <north>41.44234537860543</north>
        <south>41.4037612242825</south>
        <east>-73.82018638989426</east>
        <west>-73.85321641890307</west>
        <rotation>13.67718681063408</rotation>
    </LatLonBox>
</GroundOverlay>
</kml>

Answer 1

Something you might want to consider (now or in future) is to use the Georeferencer plugin in QGIS to do this kind of thing. You can load e.g. Google Maps into a QGIS layer using the Quick Map Services plugin¹ then use the Georeferencer to, well, georeference your image against it. On occasion the plugin can be a bit finicky but over all it works very well.

A tutorial for doing this is available.

¹ Using the OpenLayers plugin isn't recommended since it's prone to crashing QGIS

Answer 2

I find the Freehand Raster Georeferencer plugin to be much easier to use than the Georeferencer plugin. It also has the benefit of being able to use image formats other than TIFF files, and it can easily export the georeferenced image with a world file that will locate it again if needed.

That avoids the need to involve Google Earth at all. In fact, it is much like the process you use to locate the image in Google Earth, insert the image, then use the options to move the image, resize it, or rotate it, to get it where you want.

You will need a base map or other layer to use to line it up with (much as you would use Google Earth's satellite images of the Earth to line up your map/image). In fact, you can load Google's satellite images as a base map in QGIS and use it to align your image with the Freehand Raster Georeferencer plugin.

My experience is the Freehand Raster Georeferencer plugin can degrade the way an image looks, but, if you export the image with a world file (that is an option with the plugin), you can then open the image in a graphics editor like Paint.net and, being careful to not change the image's dimensions or rotation at all (not one pixel), use it to smooth lines or otherwise improve the image, and then, you can use the world file to load the edited image back in QGIS and it will be as beautiful as you made it in Paint.net/Gimp/Krita/etc. You need to make sure the file names stay the same for the image and world file as when they were exported. Pretty painless, and you can get outstanding results. A possible drawback is you apparently cannot warp an image if that is needed to get it to align properly, but my guess is that is not likely needed unless the image covers a large area on the surface of the Earth.

You can find info on the plugin and how to use it here https://gvellut.github.io/FreehandRasterGeoreferencer/ and a search in Google will find tutorials.

Its developer says the plugin has 2 main limitations:

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The lack of support for all the GDAL raster formats: The plugin actually implements its own raster layer that uses Qt to perform reading and only some raster formats are supported (BMP, JPEG, PNG, TIFF).

It only supports affine transformations (without shearing) and not the full set of transformation algorithms (including rubbersheeting) the standard QGIS georeferencer provides.

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