colorRamps.byName("Blue 6") doesn’t work with rasterstretchrenderer

[Nicolas_]

Hello,

I have setup the following renderer for my raster layer. It works very well:

let rendererRaster = new RasterStretchRenderer({
    statistics: [[0, 100, 0, 0]],
    stretchType: "min-max",
    colorRamp: new MultipartColorRamp({
        colorRamps: [
            { algorithm: "cie-lab", fromColor: new Color([255, 255, 217, 255]), toColor: new Color([199, 233, 180, 255]) },
            { algorithm: "cie-lab", fromColor: new Color([199, 233, 180, 255]), toColor: new Color([127, 205, 187, 255]) },
            { algorithm: "cie-lab", fromColor: new Color([127, 205, 187, 255]), toColor: new Color([65, 182, 196, 255]) },
            { algorithm: "cie-lab", fromColor: new Color([65, 182, 196, 255]), toColor: new Color([29, 145, 192, 255]) },
            { algorithm: "cie-lab", fromColor: new Color([29, 145, 192, 255]), toColor: new Color([34, 94, 168, 255]) },
            { algorithm: "cie-lab", fromColor: new Color([34, 94, 168, 255]), toColor: new Color([37, 52, 148, 255]) },
            { algorithm: "cie-lab", fromColor: new Color([37, 52, 148, 255]), toColor: new Color([8, 29, 88, 2555]) },
        ]
    })
});

But now I would like to use the preset colorramps that you show here: https://developers.arcgis.com/javascript/latest/visualization/symbols-color-ramps/esri-color-ramps/#... 

So I try doing the following, but It doesn't work (the raster is shown as black and white):

let rendererRaster = new RasterStretchRenderer({
    statistics: [[0, 100, 0, 0]],
    stretchType: "min-max",
    colorRamp: colorRamps.byName("Blue 6")
});

 How can I use the preset coloramps?

[UndralBatsukh]

Hi there, 

The smartMapping colorRamps return array of colors so you'd have to pass the colors to the fromColors to toColors. At 4.29, we introduced esri/smartMapping/raster/support/colorRamps and they are used to create colorRamps for raster renderers. This sample shows how to use it: https://developers.arcgis.com/javascript/latest/sample-code/sandbox/?sample=layers-imagery-renderer

[Nicolas_ · Accepted solution]

Following the example you provided, I changed my code to:

let rendererRaster = new RasterStretchRenderer({
    statistics: [[40, 145, 0, 0]],
    stretchType: "min-max",
    colorRamp: colorRamps.createColorRamp(colorRamps.byName("Precipitation"))
});

This work. Do note that Typescript is expecting ".colors" after "byName". This is wrong and I had to add //ts-ignore above the line.

I see that the named colorramps are limited to about 50 ramps compared to 512 ramps on the website. Is this a bug? For exemple, the ramp "Blue 6" doesn't seems to work in my code.

Edit: For my last question, I see that the ramps in "@arcgis/core/smartMapping/raster/support/colorRamps" are not the same as "@arcgis/core/smartMapping/symbology/support/colorRamps". Thats why "Blue 6" doesn't exist for rasters.