Stitching plans before georeferencing in QGIS

[Colin Mazengarb]

While not strictly a QGIS question I think this problem may be something others have pondered and solved! 

My problem: I am georeferencing some old plans using QGIS. Unfortunately, some plans have been scanned into 4 parts and while I can georeference each one it is difficult to get them all perfectly aligned with respect to each other. My thoughts are to stitch them together first somehow and then georeference as a single image. Has anyone had this issue and found a good solution? 

[adriano...@gmail.com]

I think I may be able to help you, Colin.

I faced a similar problem stitching / merging Granville Stapylton’s 1839 maps of early Brisbane.

I had two maps that needed to be stitched / merged into one image for georeferencing using QGIS.

I solve the problem by using GIMP, a free open-source photo editor https://www.gimp.org/downloads/index-comments.html

Once I got the hang of using the program, I found it quite east to do.

Adrian

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[Colin Mazengarb]

Thanks Adrian. I will give Gimp a go. I have been trying Hugin which should do it according to a forum but haven't cracked it yet.

Cheers

Colin

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[Adam Steer]

Hugin is really good if your images have enough overlap / enough common features. 

If image <--> image distortion is an issue in gimp/inkscape, hugin can help. Although the process is more involved. I've done it a lot with ice core imagery, although I (eventually) collected the imagery with the process in mind.

Here's the tutorial I started from: 

https://hugin.sourceforge.io/tutorials/scans/en.shtml

Hope that helps,

Adam

[Andy Tice]

Hi all

On the note of GIMP. There's a relatively intuitive plugin which allows you to (kind of) work between qgis and gimp.

https://github.com/lmotta/gimpselectionfeature_plugin/wiki

I've used it in the past to shift already georefernced rasters around a little bit.

Cheers

Andy

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[Barry Cotton]

Hi Colin,

I am a geological map maker and have been since 1970.  To make my maps I like to gather what has been done before and so I routinely face your predicament.  There is no book written on the subject but it could fill a book.  Each item one collects has a different solution, which will depend on what you've got and how it was originally made, which usually comes down to when it was made and by whom.  Did they understand projections, were they geometrically artistic, etc, etc.

I can answer your question and tell you what to do if you can be more specific on what was chopped into pieces, how they were chopped into pieces and what location information is on them.  I would also need to know what you want to end up with, eg, do you care where it is on Planet Earth or just need to rejoin the pieces.

As a generalization, my instinct tells me that you would need to prepare the bits first, then splice them together.  You will have to be sure that they are each oriented the same and each will have to have enough overlap (or enough location information) to georeference them individually.

I am a lazy retiree so have a bit of time to spare for you if you can't otherwise solve the problem.  Send me pictures of the pieces and a brief description of what you want to use them for when you're finished and how you got them in the first place.

I'm well versed in QGIS and Mapinfo and have a 1996 version of Photoshop which is still my preferred image editor.

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[box...@iinet.net.au]

The other option is to use the freehand georeferencer plug-in which allows you to bring in a raster and stretch/rotate etc to fit an underlying image like Google Earth or an existing map. It is a bit fiddly but it does work.

 

Cheers Grant

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[Marco Giana]

I would use an image software to clip and put the images in the correct location to a single image then georeference.

I use https://www.getpaint.net/

Cheers

Marco

On Fri, 19 Apr. 2024, 6:52 pm Colin Mazengarb, <colin...@gmail.com> wrote:

While not strictly a QGIS question I think this problem may be something others have pondered and solved! 

My problem: I am georeferencing some old plans using QGIS. Unfortunately, some plans have been scanned into 4 parts and while I can georeference each one it is difficult to get them all perfectly aligned with respect to each other. My thoughts are to stitch them together first somehow and then georeference as a single image. Has anyone had this issue and found a good solution? 

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