How to use a raster function?

BernardoArevalo

I was wondering if anyone had any experience or examples rendering raster functions as a raster layer.

Every time I pass a raster function with the mask_function the whole raster isn't shown.

I use a function of the following

{  "raster_function":{"type":"Mask_function"},  "raster_function_arguments":  {    "nodata_values":{"double_array":["0.0","1.0","2.0","3.0","4.0","5.0","6.0","7.0","8.0","9.0","10.0","11.0","12.0","13.0","14.0","15.0","16.0","17.0","18.0","19.0","20.0","21.0","22.0","23.0","24.0","25.0","26.0","27.0","28.0","29.0","30.0","31.0","32.0","33.0","34.0","35.0","36.0","37.0","38.0","39.0","40.0","41.0","42.0","43.0","44.0","45.0","46.0","47.0","48.0","49.0","50.0"],"type":"Raster_function_variable"},    "nodata_interpretation":{"nodata_interpretation":"all","type":"Raster_function_variable"},    "raster":{"name":"raster","is_raster":true,"type":"Raster_function_variable"},    "type":"Raster_function_arguments"  },"type":"Raster_function_template"}

I have also tried using instead of string values just regular values in the form of [0.0, 1.0, 2.0, ...]

My code looks like the following

class func loadOnlineRasterImage(function: String, complete: @escaping (AGSRasterLayer) ->()) {

    let x = URL.init(string: "https://utility.arcgis.com/usrsvcs/servers/11e0cb598d77463cbe3b90d5e53f37d6/rest/services/WorldElevation/Terrain/ImageServer")

    let imageServiceRaster = AGSImageServiceRaster.init(url: x!)

    let serviceInfo = imageServiceRaster.serviceInfo

    let renderingRule = AGSRenderingRule(renderingRuleJSON: [

      "rasterFunction": function,

      "format":"jpg"

      ])

    

    imageServiceRaster.renderingRule = renderingRule

    imageServiceRaster.load { (error) in

      if let error = error {

        print(error)

        return

      }

      

      let rasterFunction = self.setRasterfunction(raster: imageServiceRaster)

      

      let finalRaster = AGSRaster.init(rasterFunction: rasterFunction)

      

      print("nardo")

      print(error)

      let rasterLayer = AGSRasterLayer(raster: finalRaster)

      complete(rasterLayer)

      

      

      

    }

  }

  

  class func setRasterfunction(raster: AGSImageServiceRaster) -> AGSRasterFunction{

    var x: [Double] = []

    for index in 0...50 {

      x.append(Double(index))

    }

    

    var xx = x.map({abc -> String in  "\(abc)"}).joined(separator: ",")

    

    

    var content = "{  \"raster_function\":{\"type\":\"Mask_function\"},  \"raster_function_arguments\":  {    \"nodata_values\":{\"double_array\":[{{replace}}],\"type\":\"Raster_function_variable\"},    \"nodata_interpretation\":{\"nodata_interpretation\":\"all\",\"type\":\"Raster_function_variable\"},    \"raster\":{\"name\":\"raster\",\"is_raster\":true,\"type\":\"Raster_function_variable\"},    \"type\":\"Raster_function_arguments\"  },\"type\":\"Raster_function_template\"}".replacingOccurrences(of: "{{replace}}", with: xyz )

    

    print(content)

    

    FileUtil.writefile(name: "hi.json", content: content  )

    

    let docDir = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)

    let mapUrl = docDir.appendingPathComponent("hi.json")

    

    let rasterFunction = AGSRasterFunction(fileURL: mapUrl)

    // initialize the arguments of the raster function

    let rasterFunctionArguments = rasterFunction.arguments

    print(rasterFunctionArguments.debugDescription)

    

    

    

    let rasterNames = rasterFunctionArguments!.rasterNames

    // assuming rasterNames has 2 entries, set the 2 rasters

    rasterFunctionArguments!.setRaster(raster, withName: rasterNames[0])

    return rasterFunction

  }

The first function uses the second function to create a raster function and load it into a new agsraster which is then placed in a layer. I know that the file is properly being written as I've checked it. I'm not sure what I'm doing wrong : \

Does anyone have any working examples or advice?

PhilipGruenler

In the loadOnlineRasterImage function, imageServiceRaster is going out of scope.  The call to load is asynchronous; when the completion block is executed and tries to use imageServiceRaster, it has gone out of scope.  With that fixed, your code is working for me.  I made two other minor changes.  I wasn't sure why you were setting the renderingRule so I removed that code.  And instead of writing the JSON to disk and reading it back, I changed it to use the fromJSON method, like this:

let rasterFunction = AGSRasterFunction.fromJSON(content, error: nil) as? AGSRasterFunction

I hope that helps.

Phil