I need help with importing aerial orthoimagery from a municipality's open data into JOSM

Help and support
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I’m trying to import imagery from this source into JOSM, but I’m not sure if it’s possible. The following are the two API links that they provide:

The first link appears to be for an ArcGIS REST endpoint, and the second is for KML which I don’t think JOSM can use.

Would anyone have any ideas for how I can use this aerial imagery in JOSM? Is there a way to modify the URL’s to probe for a hidden WMS endpoint? Could I somehow export the entire tileset to import into JOSM locally?

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The imagery can be used like a WMS with JOSM using the “Export Image” function:
https://geoservices.mapleridge.ca/image/rest/services/Orthoimagery/2023_7_5cm/ImageServer/exportImage?f=image&bbox={bbox}&bboxSR={wkid}&imageSR={wkid}&size={width},{height}&format=jpgpng

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Oh my god… I’ve been trying to figure this out for so long. For my future reference, how did you know to use that specific link, and how did you know the exact way to format it?

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One interesting thing that I’ve noticed is that the same zoom level in JOSM seems less sharp than the same zoom level in the online map. For example:

What’s up with that?

EDIT: Ah, this appears to be due to the “Tile Size” setting in WMS settings being to small (512). I increased it to 2000 and it seems to match the source now.

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Would anyone know exactly what is going on to cause this?

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Yes. It has to do with the “default” max zoom level. IIRC, it is 20. The max zoom for the online version is probably 21 or 22.

I would recommend (if the source allows it) that you add the necessary information to Maps/Canada – JOSM so that other people can use the source. This will let you set the maximum zoom level, the minimum zoom level, and so on. Read https://josm.openstreetmap.de/wiki/Maps for the various options and what they do.

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Naturally that includes adding it to the Editor Imagery Index, not doing that is kind of shooting yourself in the foot.

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Adding it to ELI doesn’t help a JOSM at all.

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Naturally it does (JOSM users that is); you don’t get iD and other editor users using inferior imagery messing up your high quality JOSM edits

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It is documented here:

Regarding the JOSM parameters, see also:
https://josm.openstreetmap.de/wiki/Maps#WebMapServicesWMS

I have already done this with another imagery:

As @vorpalblade-kaart has already pointed out, this is probably due to the max zoom level. The desired max zoom level can be specified at the beginning of the URL in JOSM:
wms[22]:https://geoservices.mapleridge.ca/image/rest/services/Orthoimagery/2023_7_5cm/ImageServer/exportImage?f=image&bbox={bbox}&bboxSR={wkid}&imageSR={wkid}&size={width},{height}&format=jpgpng

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Where would I find the information needed to confirm this? Also, why does increasing the tile size appear to fix the issue if it has to do with the max zoom level?

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It seems pretty intuitive to me.

If the same number of pixels is requested for a smaller area on the ground (= higher zoom, smaller bbox), then the physical resolution increases.
Example of your area above:

512×512 36.2 KB

512×512 26.6 KB

If more pixels (size) are requested for the same area on the ground (bbox), the physical resolution also increases.
Example of your area above:

2000×2000 360 KB

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By “confirm” I was more meaning: where should I look to find, with certainty (rather than trial and error), that data source’s max zoom?