@geogirafe/lib-geoportal/tools/raster/rasterutils.js

GeoGirafe is a flexible application to build online geoportals.

// SPDX-License-Identifier: Apache-2.0
import { fromUrl } from 'geotiff';
export async function extractGeoTransform(image) {
    const tiePoint = (await image.getTiePoints())[0];
    const pixelScale = image.getFileDirectory().getValue('ModelPixelScale');
    return { tiePoint, pixelScale };
}
export function mapToPixel(transform, mapX, mapY) {
    const pixelX = Math.round((mapX - transform.tiePoint.x) / transform.pixelScale[0]);
    const pixelY = Math.round((transform.tiePoint.y - mapY) / transform.pixelScale[1]);
    return [pixelX, pixelY];
}
export function pixelToMap(transform, pixelX, pixelY) {
    const mapX = transform.tiePoint.x + pixelX * transform.pixelScale[0];
    const mapY = transform.tiePoint.y - pixelY * transform.pixelScale[1];
    return [mapX, mapY];
}
export async function getImage(url) {
    const tiff = await fromUrl(url);
    const image = await tiff.getImage();
    return image;
}
export async function getPixelValue(image, transform, coordinates) {
    const [pixelX, pixelY] = mapToPixel(transform, coordinates[0], coordinates[1]);
    const window = [pixelX, pixelY, pixelX + 1, pixelY + 1];
    const width = image.getWidth();
    const height = image.getHeight();
    let pixelValue;
    if (pixelX >= 0 && pixelX < width && pixelY >= 0 && pixelY < height) {
        const pixelData = (await image.readRasters({ samples: [0], window: window }));
        pixelValue = pixelData[0][0];
    }
    else {
        pixelValue = null;
    }
    return pixelValue;
}