pulldata @layer for rasters

AMur

Hello,

In Survey123 I am trying to query a DEM raster layer from map lick or coordinates with pulldata @layer but cannot find how to read the stretch.pixel value. Under the layer's service page, Fields is None so not sure what to put in for "attributes"

AMur

I have tried to use javascript to perform the action but am running in to issues with the returned json. I am connected through an Enterprise account but if I use the parent url the below script returns the error 'Token Required'. The error in Survey123 is always the same. I can use a child layer and paste the identify url in a browser but it will only return the layer attributes, never the value of the coordinates.

This script creates the following url (I have removed the url and lat/lon info)

<url>/identify?geometry=%7B"x"%3A<lon>%2C"y"%3A<lat>%2C"spatialReference"%3A%7B"wkid"%3A4326%7D%7D&geometryType=esriGeometryPoint&returnGeometry=false&returnCatalogItems=false&f=json 

 

// rasterPixelValue.js

// Call from XLSForm: pulldata("@javascript", "rasterPixelValue.js", "getRasterValue", imageServiceUrl, longitude, latitude)

 

function getRasterValue(imageServiceUrl, longitude, latitude) {

// Validate inputs

if (!imageServiceUrl || !longitude || !latitude) {

return "Error: Missing required parameters (imageServiceUrl, longitude, latitude)";

}

 

// Convert coordinates to numbers

const lon = parseFloat(longitude);

const lat = parseFloat(latitude);

 

if (isNaN(lon) || isNaN(lat)) {

return "Error: Invalid coordinates";

}

 

try {

// Build the identify request URL

const identifyUrl = imageServiceUrl.endsWith('/')

? imageServiceUrl + 'identify'

: imageServiceUrl + '/identify';

 

// Create the geometry parameter

const geometry = JSON.stringify({

x: lon,

y: lat,

spatialReference: { wkid: 4326 }

});

 

// Build request parameters manually

const params = [

'geometry=' + encodeURIComponent(geometry),

'geometryType=esriGeometryPoint',

'returnGeometry=false',

'returnCatalogItems=false',

'f=json'

];

 

const requestUrl = identifyUrl + '?' + params.join('&');

 

// Make synchronous request (required for Survey123 pulldata functions)

const xhr = new XMLHttpRequest();

xhr.open('GET', requestUrl, false); // false = synchronous

xhr.withCredentials = true;

xhr.send();

 

if (xhr.status === 200) {

const response = JSON.parse(xhr.responseText);

 

// Check for errors in response

if (response.error) {

return "Error: " + response.error.message + " " +requestUrl;

}

 

// Extract pixel value

let pixelValue = null;

 

if (response.value !== undefined && response.value !== null) {

pixelValue = response.value;

} else if (response.values && response.values.length > 0) {

// For multi-band rasters, return first band or comma-separated values

pixelValue = response.values.length === 1 ? response.values[0] : response.values.join(',');

} else if (response.properties && Object.keys(response.properties).length > 0) {

// Sometimes pixel data is in properties

const keys = Object.keys(response.properties);

pixelValue = response.properties[keys[0]]; // Return first property value

}

 

// Return the pixel value or "No Data" if null/undefined

return pixelValue !== null && pixelValue !== undefined ? pixelValue.toString() : "No Data";

 

} else {

return "Error: HTTP " + xhr.status + " - Unable to query image service";

}

 

} catch (error) {

return "Error: " + error.message;

}

}

 

 

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