topic Re: Javascript Api Identify Raster pixel value in ArcGIS JavaScript Maps SDK Questions

Javascript Api Identify Raster pixel value

BeakalGobena — Wed, 20 Aug 2014 14:02:44 GMT

I have this map loaded using the ArcGIS API

http://ags.servirlabs.net/ArcGIS/rest/services/ReferenceNode/TRMM_30DAY/MapServer

I want to let the user click on the raster layer and display the pixel value at that specific x,y location in a pop up window. While googling I found this example

https://developers.arcgis.com/javascript/jssamples/find_popup.html

explaining how to use IdentifyTask. Can I use this feature for a raster layer plus the data is already loaded do I need to make an extra request to get the values every time the user clicks on the layer?

Re: Javascript Api Identify Raster pixel value

TimWitt2 — Wed, 20 Aug 2014 14:12:52 GMT

Here you go!

Edit fiddle - JSFiddle‌

Re: Javascript Api Identify Raster pixel value

RiyasDeen — Thu, 21 Aug 2014 00:33:07 GMT

Hi Beakal,

Noticed that Tim's sample is displaying the pixel's attributes like colour and layer name, i understand you are interested in the value of the pixel.

I have modified find_popup sample to display the pixel value.

Edit fiddle - JSFiddle‌

Re: Javascript Api Identify Raster pixel value

BeakalGobena — Fri, 22 Aug 2014 14:22:49 GMT

Thanks Tim and Riyas and for the reply, IdentifyParameter and IdentifyTask is the write approach.

But I ran into another problem, on my page I'm loading four different layers at a time while the IdentifyParameter object accepts only one url as a parameter. Note that the layers are not in the same map service, they are in a different urls and different locations.

When the users click on any of the layer, I want to get the pixel values from the clicked layer.

Is this some thing possible?

Re: Javascript Api Identify Raster pixel value

AudyBarnett — Thu, 13 Nov 2014 17:32:22 GMT

Thanks Riyas. This is helpful. However, when I try to use your code I receive "undefined" as my pixel value in the pop up. My map service shows in the app and I can click to make the pop up show, but I do not receive a pixel value. Any ideas?

Thanks.

Re: Javascript Api Identify Raster pixel value

NMWater — Thu, 05 May 2016 15:49:30 GMT

Hi Audy,

I have the same problem currently, I was wondering if you ever figured out how to tackle this issue? I still get undefined when trying to find the pixel value.

Many Thanks.

Re: Javascript Api Identify Raster pixel value

Anonymous User — Thu, 02 Jun 2016 19:37:20 GMT

Tim Witt Riyas Deen

Thanks! Teamwork!!

We needed this too. It just needed a small fix from Riyas' example. Here is an updated working sample, using our DEM:

http://jsfiddle.net/kevinmSAGIS/L834u2nt/4/

Identify cell value with Popup in a mapServer raster

I had to add the following line because there's a space in Pixel Value:

"Pixel Value is : " + feature.attributes[ 'Pixel Value']);

Re: Javascript Api Identify Raster pixel value

Anonymous User — Thu, 02 Jun 2016 19:47:40 GMT

see my reply at the bottom for the fix NM Water

Re: Javascript Api Identify Raster pixel value

LloydBronn — Sun, 25 Sep 2016 18:13:12 GMT

This is great! I want to incorporate it into a script I'm working on. Will it work to reference the 3.17 API instead of 3.10?

Thanks!

Re: Javascript Api Identify Raster pixel value

RobertScheitlin__GISP — Sun, 25 Sep 2016 18:19:12 GMT

Absolutely

Re: Javascript Api Identify Raster pixel value

LloydBronn — Sun, 25 Sep 2016 18:44:28 GMT

When I switch the reference to 3.17, the map gets all screwed up (only certain tiles show up) and the identify widget becomes a line of text way up in the left corner of the map.

Re: Javascript Api Identify Raster pixel value

RobertScheitlin__GISP — Sun, 25 Sep 2016 19:47:13 GMT

Did you change the CSS references too?

Re: Javascript Api Identify Raster pixel value

LloydBronn — Tue, 27 Sep 2016 13:58:09 GMT

I did. There is only one CSS reference in the example script. <link rel="stylesheet" href="http://js.arcgis.com/3.10/js/esri/css/esri.css">.

Re: Javascript Api Identify Raster pixel value

RobertScheitlin__GISP — Tue, 27 Sep 2016 14:09:14 GMT

Lloyd,

What did you update that url to?

It was:

you should change it to:
<link rel="stylesheet" type="text/css" href="https://js.arcgis.com/3.17/esri/css/esri.css">

Re: Javascript Api Identify Raster pixel value

LloydBronn — Tue, 27 Sep 2016 14:20:46 GMT

I changed both to 3.17. It works perfectly with 3.10, but goes crazy with 3.17. The only other thing I changed was the center and zoom of the map.

Re: Javascript Api Identify Raster pixel value

RobertScheitlin__GISP — Tue, 27 Sep 2016 14:26:43 GMT

Lloyd,

Pay very close attention to the CSS URL the URL you are trying to use is incorrect. If you copy the CSS link I provided you will not have an issue.

Re: Javascript Api Identify Raster pixel value

LloydBronn — Tue, 27 Sep 2016 14:29:00 GMT

That works, thanks!!

Re: Javascript Api Identify Raster pixel value

Anonymous User — Thu, 22 Dec 2016 14:44:46 GMT

GreetingsDerek Law‌ This would be an excellent feature to support in ArcGIS Online webmaps for identifying raster pixels in popups. If webmaps support it natively we can use it for creating fully online Esri-cloud hosted WebApp Builder sites. Any thought if this might be implemented at some time in the future?

Re: Javascript Api Identify Raster pixel value

DerekLaw — Tue, 22 Jun 2021 08:31:57 GMT

Hi Kevin,

I see you've already submitted your enhancement suggestion on the ArcGIS Ideas threads,

https://community.esri.com/ideas/12329

And I can't comment on if and when this enhancement would be implemented at this time, sorry. It could probably use some more votes to make it a higher priority.

Hope this helps and happy holidays,

Re: Javascript Api Identify Raster pixel value

GIS — Thu, 14 Mar 2019 11:29:15 GMT

Hi,
Does anybody know if a custom widget for ArcGIS Online with this functionality has been created in the mean time and if so, where I could find it?