Tile Math

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Tile Math

帖子ddrinka » 2018-01-30 0:30

This ones a little crazy...

I'd like to be able to subtract the alpha value of one layer from the alpha value of another.

My goal is to display the Strava Global Heat Map, but without any roads. I mountain bike and I only want to see off-road trails. I can add a layer that only displays roads of a certain size, but I don't want to see that layer. I want to not see the contents of another layer anywhere the first layer appears.

I know, it's crazy, but I'm thinking about creating an online source to do this math for me, and it would sure be easier to do the math on the client side.
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Re: Tile Math

帖子Zax » 2018-02-03 4:54

what do u mean about Layers? are they raster or vector? online map source? or from local file? what about the file format?
Zax Zeng
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Re: Tile Math

帖子ddrinka » 2018-02-09 20:19

Raster online sources--PNG with alpha channel.
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Re: Tile Math

帖子Zax » 2018-02-11 13:05

ddrinka 写道:Raster online sources--PNG with alpha channel.


Although it is applicable, but there is no strong reason for us to implement it as a public function. We have to do many changes to the rendering, but only plenty of users need.

Anyway, as a suggestion, you can try the Map Download function with a custom shape to limit the area, which might work with a similar result as you expected.

First, draw a polygon that contains only regions you are interested in, save it to the User Data.
Then, try the map download function, while specifying downloading region, tap Reset and choose "From User Data", and pick the polygon you just create.
Start Downloading the the downloaded map would only be visible within the polygon you specified.
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