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Home - General / All posts - Escape from Imagery Prison
384 post(s)
#11-Jul-19 22:19

Using v8 I linked a Bing satellite image, and used Image --> Download to cache up to L3 for a pretty large area. I then used Tools --> Make Image --> Entire Component at Current Scale whilst zoomed to 1:10k to render an image component of 50216 x 94416 pixels. That "made" image component came out with all sorts of artifacts, unfortunately, as you can see here, including the correctly-rendered area representing the window extents when I invoked the command:

The temporary directory on disk contains ~150k jpg files downloaded from Bing. Not ALL of those jpgs were downloaded as part of this effort, but all the data requested on this effort are there.

When I use Release 9 to connect to that directory using the "Folder: library" (with Reverse Y) datasource, the datasource's image displays correctly, but any attempt to export the image as a TIF throws the error "Tile size is too large". If I copy the datasource's table and paste into the Release 9 project pane, the progress indicator reports speed of ~70 B/s, which I am confident is equivalent to "this will never work, you idiot". SELECT * INTO [local] FROM [DS]::[Image] proceeds at ~50 B/s.

What's the best way to get an AOI of this directory of images, or indeed that original linked Release 8 component (for which we've done the lengthy download) converted to a TIF on disk?

Good times, thanks!



5,491 post(s)
#12-Jul-19 09:50

If I copy the datasource's table and paste into the Release 9 project pane, the progress indicator reports speed of ~70 B/s,

Perhaps I misunderstand, but I think that's asking the web server that provides the image to give you the entire content it has for the entire image, not just that part of it in view, down to the smallest resolution. The slow speed is a slow response from the web server when you ask it to download all it has.

You can see what the size of the full image and table are by looking at the Contents - Component pane for the image and table in the data source. Look at Bing, for example, and it's very big.

As to generating an image from what you have, it seems it wasn't all downloaded if 8 showed it with the strange array of lines. If you don't have all of the image, that won't work with 9.

I think what you really want is a "make image" tool within 9 that automatically scrapes web servers to build an image.


8,805 post(s)
#12-Jul-19 10:20

...which would run headfirst into quite reasonable licensing issues?


5,491 post(s)
#12-Jul-19 10:31

I guess that would depend on the web server you are using, what the API key you are using buys you, and so on.

For example, there are plenty of web servers out there (government sites, etc.) providing public domain imagery that you are perfectly free to scrape into a local image.


8,805 post(s)
#12-Jul-19 10:50

Yes. This is Bing. Free lunch.

384 post(s)
#12-Jul-19 17:40

Thanks Dimitri. I needed to be more clear in my original post; I was jacked on coffee.

The ~70 B/s performance (89 B/s in the next screen cap) occurs when attempting to copy a "Folder: library" datasource's table into a Release 9 project, not when trying to copy a Bing webserver datasource or something maniacal like that.

In this next image, you can see that the folder (which was filled by Release 8's "Download Image" tool) correctly displays all data when loaded in Release 9 as a "library". All the data are there.

Why Release 8's "Make Image" tool would fail to correctly render the entire scene I can only speculate.

The Release 8 project reports that the levels I seek (L3 max) have been successfully downloaded:

Attempts to "Make Image" (Entire Component at Current Scale) for less aggressive scales also produce weirdness, correctly rendering only the window extents that had been visible when invoking the tool. Here's an attempt when zoomed 1:100k (my earlier attempt had been at 1:10k):


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