Survey123 Spatial Analysis/Overlapping polygons

CherylWheeler11

Hi,

Would anybody know whether there is way within Survey123 to check whether a new polygon being collected via a geoshape question overlaps an existing polygon/record collected in previous surveys? So, some kind of constraint for spatial functionality.

Many thanks for any suggestions.

Ruth_JiatengXu

Hi,

There is no existing function to do this, however, Survey123 does support the custom JS function.

Here are some good resources:

 Blog: https://community.esri.com/t5/arcgis-survey123-blog/extending-survey123-smart-forms-with-custom-js-f... 

Doc: https://doc.arcgis.com/en/survey123/desktop/create-surveys/pulldatajavascript.htm (Please pay attention to the known limitations at the end of this doc)

I have also attached a sample XLSform (Please change the feature layer url in the pulldata function) and a Javascript code (Please take the code and save it as .js file, then put the js. file into the scripts folder as described in the documentation).

The following code can do simple overlap detection and returns the count of the existing polygons that are overlapping.

 

 

function overlapDetection(geometry, token, featurelayer_url) {
    // If there is no geometry input, output null
    if (!geometry) {
        return "Wait for input geometry.";
    }

    // If the survey is submitted in the webapp, convert the geometry to object
    if (typeof(geometry) != "object") {      
        var geoArray = geometry.split(';');
        geoArray.forEach(ArraytoAA);
        var geoObject = {"rings": [geoArray]};
    } else {
        var geoObject = geometry;
    }

    var geoString = JSON.stringify(geoObject);

    // Change the parameters in the query URL to work with different geometryType, spatialRel, etc.
    // Ref: https://developers.arcgis.com/rest/services-reference/query-feature-service-layer-.htm
    var url = featurelayer_url+"/query?where=1%3D1&geometry="+geoString+"&geometryType=esriGeometryPolygon&spatialRel=esriSpatialRelOverlaps&units=esriSRUnit_Meter&returnCountOnly=true&f=json";

    if (token) {
        url =  url+"&token="+token;
    }

    var xhttp = new XMLHttpRequest();
    xhttp.open("GET", url, false);
    xhttp.send();

    if (xhttp.status!==200) {
        return (xhttp.status);
    } else {
        var responseJSON=JSON.parse(xhttp.responseText)
        if (responseJSON.error) {
            return JSON.stringify(responseJSON.error);
        } else {
            return JSON.stringify(responseJSON.count);
        }
    }
}

function ArraytoAA(item,index,array) {
    var coord = item.split(' ').map(Number)
    array[index] = coord;
}

 

 

 Thanks,

Ruth 

Test pulldata JS overlap 2.xlsx