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Buffer tool for Survey123 Map

MicheleDe_Santis

Hi to all,

is it possible to add a buffer tool on a Suvey123 Map? I would like to draw a buffer (radius 100m) on my position when the user click on a button. The buffer should be stay fixed on map and erased when the user click on another button. How Can I implement this function?

Thanks to all

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JohnHasthorpe

Hi Michelle

Currently we don't support this functionality. I could get this added as an enhancement request - but in order to do so, could you provide more details of your workflow and what you are trying to acheive.

Thanks

John

MicheleDe_Santis

Hi John,

in our application surveyors go into field to sample trees and plants. They wants create a buffer on the map because they wants move inside it. The law imposes samples along 100m from sick plant. Inside our organization does we can modify the source code for this need?

Thanks

Michele

DanielDery

I developed some Javascript functions to create a buffer around a point/current position. This script uses the UTM coordinates from the point, calculates the UTM coordinates of 360 points around it, converts them all to Lat/Lon and creates a text string to be used in the geoshape Calculate column. You will need to save the .txt file as .js because javascript attachments are surprisingly not supported here.

Please note that this script is not perfect and can be improved. It can also be used in a Repeat to create multiple buffers around the center point.

Daniel Dery

test_buffer.xlsx

buffer360coordinates.txt

MichelleWilliamsERM

WOW, and thank you @DanielDery that looks sexy.

MonmouthNJGIS

Good Morning Daniel! We love this approach and gave it a try in one of our org's surveys, but we can't get the desired results. We tried on a blank survey as well using the files provided and could not replicate that either. If you're able to take a look at our survey file, do you see any glaring issues?

Thanks in advance for any advice!

form.xlsx

rrhee_bcfpd

Not sure if you're still looking for a solution, but I got it working on Survey123Connect 3.18 with a few tweaks.

Change "round((...), 7)" to (...).toFixed(7) in lines 114 and 115
If you want to run it on a web-based form, replace "center_X" with "parseFloat(center_X)" in line 112 and 113
* I currently have the question that runs the javascript script to have a field length of 10000 on a null field, but it doesn't look like Daniel did the same. Not 100% sure if it's required, but might be worth a try
* I also added a second question that takes the text from the question running the javascript and uses substr(${...}, 0, string-length(${...} - 2)) to trim off the trailing "; " that gets appended to the last coordinate pair, but again, it doesn't look like Daniel did the same.

I attached my modification of the script below, but I did shrink the script down to a single function so it will look different, but it's doing the same thing. No guarantee it will work, but I also ran into a few issues, but this solution is possible with a little tweaking and experimentation with the script.

buffer360coordinates_modified.txt

GrishaPost

Thank you, @DanielDery and @rrhee_bcfpd!

MichelleWilliamsERM

I'm having a weird issue. OB1, you're my only hope.

I'm using the form and the updated code from above, but my buffer isn't around my point in Beaumont, CA; it's in Arkansas. Have you encountered this issue before, and if so, how did you resolve it?

rrhee_bcfpd

Oops, looks like I was a bit short-sighted on my last post, and I hard-coded my UTM zone instead of leaving that as a function parameter. Likewise, I also scratched the part of the script that accounts for northern/southern hemispheres for simplicity, so that would require some modification for use in the southern hemisphere.

For the UTM zone, just replace:

The function definition line "function generateBuffer..." with "function generateBufferCoordinates(zone, center_Y, center_X, buffer_dist) {"
Line 49 starting with "var buff_lon = (((15 > 0...", replace the line with "var buff_lon = (((zone > 0) && (6 * zone - 183.0) || 3.0) - _a3).toFixed(7);"
Then just make sure you're passing the UTM Zone parameter as the first parameter on the pulldata calc where the js call is being made

Alternatively, if you know that all of your operations are occurring in the same UTM Zone (like I did), you can simplify the script and ignore step 1 and 3 and just swap out the two "15" values in step 2 with "11" for California.

MichelleWilliamsERM

Thank you for your quick response. I'm relearning scripting and missed the hard-coding.

MichelleWilliamsERM

My team at ERM made some changes to get this to work for us (we opened it up for the US.

* Javascript function to create a buffer around a last known point.

* Script credits:

* DanielDery | https://community.esri.com/t5/arcgis-survey123-questions/buffer-tool-for-survey123-map/td-p/846713?attachment-id=78542

* Modified by Ryan Rhee - Boone County Fire Protection District/MO-TF1

* Modified by Michael Stead from ERM, and Michelle Williams Survey123 Jedi

* DOES NOT PULL FROM XY

function generateBufferCoordinates(center_Y, center_X, zone_utm, buffer_dist) {

// Single function to perform buffer algebra and return list of coordinates as string object

// *center_Y* and *center_X* must be passed into the function as UTM coordinates

// *buffer_dist* must be passed into the function in meters (m)

var coordinates = '';

// Empty string of coordinates to be populated

for (var angle_deg = 0.0; angle_deg < 360.0; angle_deg+=1.0) {

// For loop iteratesd over all angles from 0 to 359 and returns a coordinate pair for the point *buffer_dist* away at *angle_deg* degrees from the point defined by *center_X*,*center_Y*

const pi = 3.14159265359;

const a = 6378137;

const e = 0.081819191;

const e1sq = 0.006739497;

const k0 = 0.9996;

// Defined variables for mathematical constants

var zone = parseFloat(zone_utm)

var buff_Y = parseFloat(center_Y)+buffer_dist*(Math.sin(angle_deg*pi/180))

var buff_X = parseFloat(center_X)+buffer_dist*(Math.cos(angle_deg*pi/180))

// Gets the UTM coordinates for the point *buffer_dist* away at *angle_deg* degrees from the point defined by *center_X*,*center_Y*

var arc = buff_Y / k0;

var mu = arc / (a * (1 - Math.pow(e, 2) / 4.0 - 3 * Math.pow(e, 4) / 64.0 - 5 * Math.pow(e, 6) / 256.0));

var ei = (1 - Math.pow((1 - e * e), (1 / 2.0))) / (1 + Math.pow((1 - e * e), (1 / 2.0)));

var ca = 3 * ei / 2 - 27 * Math.pow(ei, 3) / 32.0;

var cb = 21 * Math.pow(ei, 2) / 16 - 55 * Math.pow(ei, 4) / 32;

var cc = 151 * Math.pow(ei, 3) / 96;

var cd = 1097 * Math.pow(ei, 4) / 512;

var phi1 = mu + ca * Math.sin(2 * mu) + cb * Math.sin(4 * mu) + cc * Math.sin(6 * mu) + cd * Math.sin(8 * mu);

var n0 = a / Math.pow((1 - Math.pow((e * Math.sin(phi1)), 2)), (1 / 2.0));

var r0 = a * (1 - e * e) / Math.pow((1 - Math.pow((e * Math.sin(phi1)), 2)), (3 / 2.0));

var fact1 = n0 * Math.tan(phi1) / r0;

var _a1 = 500000 - buff_X;

var dd0 = _a1 / (n0 * k0);

var fact2 = dd0 * dd0 / 2;

var t0 = Math.pow(Math.tan(phi1), 2);

var Q0 = e1sq * Math.pow(Math.cos(phi1), 2);

var fact3 = (5 + 3 * t0 + 10 * Q0 - 4 * Q0 * Q0 - 9 * e1sq) * Math.pow(dd0, 4) / 24;

var fact4 = (61 + 90 * t0 + 298 * Q0 + 45 * t0 * t0 - 252 * e1sq - 3 * Q0 * Q0) * Math.pow(dd0, 6) / 720;

var lof1 = _a1 / (n0 * k0);

var lof2 = (1 + 2 * t0 + Q0) * Math.pow(dd0, 3) / 6.0;

var lof3 = (5 - 2 * Q0 + 28 * t0 - 3 * Math.pow(Q0, 2) + 8 * e1sq + 24 * Math.pow(t0, 2)) * Math.pow(dd0, 5) / 120;

var _a2 = (lof1 - lof2 + lof3) / Math.cos(phi1);

var _a3 = _a2 * 180 / Math.PI;

var buff_lat = (180 * (phi1 - fact1 * (fact2 + fact3 + fact4)) / Math.PI).toFixed(7);

var buff_lon = ((((zone) > 0) && (6 * (zone) - 183.0) || 3.0) - _a3).toFixed(7);

// Performs conversion algebra to convert UTM coordinates to decimal degrees and rounds points to 7 decimal places

var coord_pair = buff_lat+" "+buff_lon+"; ";

coordinates += coord_pair;

// Concatenates strings to following format: "lat1 long1; lat2 long2; "

// Concatenates coordinate pair to stringified list of pairs

}

return coordinates;

}

Rebecca_LiljaFS

This is great work! Has anyone successfully applied this method to buffer a line?

rrhee_bcfpd

Not 100% sure, but it might be possible. You would need to find a way to pull an array of coordinates for all vertices in your line or use repeat geopoint questions to construct that array and the geotrace simultaneously (https://community.esri.com/t5/arcgis-survey123-questions/exposing-geotrace-and-geoshape-vertices-for/td-p/1283989). JavaScript would then need to loop through that array to determine each vertex in the buffer polygon. However, the script would get substantially more complex if it needs to handle parsing the correct angle for each vertex to buffer out along.

If it's not required to see the buffer on the same form as the one you're collecting the line on, you can use webhooks to trigger a function hosted on AWS or Azure to generate the buffer after the survey is submitted, or even use PowerAutomate or Make.com to make a series of requests to the ArcGIS REST API's buffer & edit endpoints with JSON parsing between each step.

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