Limit in region mapping

[josecarlosrodriguezcortes]

Hello, I'm having a problem with WMS region mapping.
I have a 250 m2 grid of terrain of data, so I have approximately 120k regions.
My problem is that Terria only draws the first 65535 elements (this is not an arbitrary number, is the last number in the styles that are provided in the docs of Terria and 2^16 - 1) so I have a map with some points drawed but a lot of them not.
I know there is a new region mapping system with vector tiles, but I don't know if this is gonna be a problem with it.
Where could I find the code that checks this so I can find this limit and, idealy, remove it?

[steve9164]

HI @josecarlosrodriguezcortes. As you've found this limit is the number of defined style colours. The region mapping style uses only blue and green pixel values.

Here is the function that does color -> region FID conversion:

terriajs/lib/Map/ImageryProviderHooks.js

Lines 30 to 54 in 6dc8cc3

	/* Recolor a raster image pixel by pixel, replacing encoded identifiers with some calculated value. */
	ImageryProviderHooks.recolorImage = function(image, colorFunc) {
	var length = image.data.length; //pixel count * 4
	for (var i = 0; i < length; i += 4) {
	// Region identifiers are encoded in the blue and green channels, with R=0 and A=255
	if (image.data[i + 3] < 255 || image.data[i] !== 0) {
	// Set any pixel that is not part of a region completely transparent
	image.data[i + 3] = 0;
	continue;
	}
	// Convert the colour of a pixel back into the identifier of the region it belongs to
	var idx = image.data[i + 1] * 0x100 + image.data[i + 2];
	// Convert that identifier into the data-mapped colour it should display as.
	var clr = colorFunc(idx);
	if (defined(clr)) {
	for (var j = 0; j < 4; j++) {
	image.data[i + j] = clr[j];
	}
	} else {
	// This is a region but we don't have data for it, so make it transparent. Possibly should be configurable.
	image.data[i + 3] = 0;
	}
	}
	return image;
	};

I think you could add regions 65536 and onwards using a red value of 1, then 2 (that way it's backwards compatible with the original r = 0 scheme for the first 65535 regions). You'll need to update that function. I think you can do that without forking terriajs given how it's exported. Just write at the top of index.js:

var ImageryProviderHooks = require("terriajs/lib/Map/ImageryProviderHooks.js")

ImageryProviderHooks.recolorImage = function(image, colorFunc) {
  // new function that decodes 0-65535 and 65536+
}

And then update the geoserver styling to match your extended scheme.

[steve9164]

Also note that WMS region mapping is deprecated and will not be supported in version 8.

[josecarlosrodriguezcortes]

Thank you so much, I've been struggling with this for some days.

I know about the new region mapping system using Vector Tiles and I'm planning to move to this version, but this was a necessity just now.