Add tile scripts

[Robinlovelace]

No description provided.

[Robinlovelace]

Update: the result looks good, but with red background instead of transparency:

[Robinlovelace]

Trying to fix it with:

gdal_translate -mask 4 dutch_slc-10m-merge2.tif dutch_slc-10m-merge2.tif

[nikolai-b]

@Robinlovelace where does the bicycle-100m.tif come from? Given you aren't colouring it (just tiling it) I'm assuming it is pre-coloured.

[Robinlovelace]

@nikolai-b we have the raw .tifs on our hds here - around 30GB each.

[Robinlovelace]

bicycle-100m.tif is a test dataset at low res.

[nikolai-b]

Does it come from https://github.com/mem48/pct-raster-tests/blob/master/R/rasterise.R#L66 ? In that case it has likely been coloured in https://github.com/mem48/pct-raster-tests/blob/master/R/rasterise.R#L62 .

I wanted to just run that script with alpha = T e.g. #3 (comment)

[Robinlovelace]

Does it come from https://github.com/mem48/pct-raster-tests/blob/master/R/rasterise.R#L66 ?

No I'm running GDAL 2.4 from bash.

I think the alpha setting, via -a 0.0 should solve it, as per latest commit to this PR.

[Robinlovelace]

I think I've diagnosed the issue. Here's a hint:

[Robinlovelace]

Fixed with

gdal_translate -a_nodata 255 dutch_slc-10m-merge2.tif dutch_slc-10m-merge2-nodata.tif

[Robinlovelace]

Hi guys, I had a good shot at this and am close to a solution. The problem is now easy to debug based on this release:

https://github.com/npct/pct-lsoa-vis/releases/download/0.0.1/dutch_slc-10m-merge2-test.tif

Reproducible example showing that it's the 255,0,0 value of the 'transparent' area that is the problem:

u = "https://github.com/npct/pct-lsoa-vis/releases/download/0.0.1/dutch_slc-10m-merge2-test.tif"
download.file(url = u, destfile = "test.tif")
remotes::install_cran("magick")
#> Skipping install of 'magick' from a cran remote, the SHA1 (2.0) has not changed since last install.
#>   Use `force = TRUE` to force installation
library(magick)
#> Linking to ImageMagick 6.9.7.4
#> Enabled features: fontconfig, freetype, fftw, lcms, pango, x11
#> Disabled features: cairo, ghostscript, rsvg, webp
i = image_read("test.tif")
i

i_fixed = image_transparent(image = i, color = "red")
i_fixed

^{Created on 2019-02-28 by the reprex package (v0.2.1)}

[Robinlovelace]

Heads-up @mem48 and @nikolai-b - see my code to debug this. Plan to try with magick to fix it as GDAL solution is not clear to me.

[Robinlovelace]

But if either of you find a GDAL solution (which I'm sure exists) that would be preferable.

[Robinlovelace]

StackExchange question: https://gis.stackexchange.com/questions/313877/how-to-convert-a-tif-file-in-which-transparency-is-implicit-to-one-in-which-it

[Robinlovelace]

Update: I have another tile set to test. Please can you give this a spin @nikolai-b - not working in the leaflet.html file contained within - see .zip attached.
raster_w-alpha.zip

[Robinlovelace]

@nikolai-b apologies for the iterative nature of this but I've finally got a test tileset that I'm confident will work. Please test these (deliberately tiny) tiles:
output2.zip