An image service can use a mosaic rule to mosaic multiple rasters on-the-fly. A mosaic rule can specify which rasters are selected, and how the selected rasters are z-ordered. It can also specify how overlapping pixels from different rasters at the same location are resolved.
For example, when using the "ByAttribute" mosaic method, the values in an attribute field are used to sort the images, and when using the "Center" method, the image closest to the center of the display is positioned as the top image in the mosaic. Additionally, the mosaic operator allows you to define how to resolve the overlapping cells, such as choosing a blending operation.
Specifying mosaic rules is useful for viewing overlapping rasters. For example, using the "ByAttribute" mosaic method to sort the rasters based on their acquisition date allows the newest image to be on top. Using "Mean" mosaic operation makes the overlapping areas contain the mean cell values from all the overlapping rasters.
How to use the sample
When the rasters are loaded, choose from a list of preset mosaic rules to apply to the rasters.
How it works
Create an ImageServiceRaster using the service's URL.
Create a MosaicRule object and set it to the MosaicRule property of the image service raster, if it does not specify a mosaic rule.
Create a RasterLayer from the image service raster and add it to the map.
Set the MosaicMethod, MosaicOperation, and other properties of the mosaic rule object accordingly to specify the rule on the raster dataset.
Relevant API
ImageServiceRaster
MosaicMethod
MosaicOperation
MosaicRule
About the data
This sample uses a raster image service hosted on ArcGIS Online that shows aerial images of Amberg, Germany.
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// Copyright 2021 Esri.//// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0//// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific// language governing permissions and limitations under the License.using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Rasters;
using Microsoft.UI.Xaml.Controls;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
namespaceArcGIS.WinUI.Samples.ApplyMosaicRule{
[ArcGIS.Samples.Shared.Attributes.Sample(
name: "Apply mosaic rule to rasters",
category: "Layers",
description: "Apply mosaic rule to a mosaic dataset of rasters.",
instructions: "When the rasters are loaded, choose from a list of preset mosaic rules to apply to the rasters.",
tags: new[] { "image service", "mosaic method", "mosaic rule", "raster" })]
[ArcGIS.Samples.Shared.Attributes.OfflineData()]
publicpartialclassApplyMosaicRule {
private ImageServiceRaster _imageServiceRaster;
// Different mosaic rules to use with the image service raster.private Dictionary<string, MosaicRule> _mosaicRules = new Dictionary<string, MosaicRule>
{
{ "None", new MosaicRule { MosaicMethod = MosaicMethod.None} },
{ "Northwest", new MosaicRule { MosaicMethod = MosaicMethod.Northwest, MosaicOperation = MosaicOperation.First} },
{ "Center", new MosaicRule { MosaicMethod = MosaicMethod.Center, MosaicOperation = MosaicOperation.Blend} },
{ "ByAttribute", new MosaicRule { MosaicMethod = MosaicMethod.Attribute, SortField = "OBJECTID"} },
{ "LockRaster", new MosaicRule { MosaicMethod = MosaicMethod.LockRaster, LockRasterIds = { 1, 7, 12 } } },
};
publicApplyMosaicRule() {
InitializeComponent();
_ = Initialize();
}
privateasync Task Initialize() {
// Create a raster layer using an image service. _imageServiceRaster = new ImageServiceRaster(new Uri("https://sampleserver7.arcgisonline.com/server/rest/services/amberg_germany/ImageServer"));
RasterLayer rasterLayer = new RasterLayer(_imageServiceRaster);
await rasterLayer.LoadAsync();
// Create a map with the raster layer. MyMapView.Map = new Map(BasemapStyle.ArcGISTopographic);
MyMapView.Map.OperationalLayers.Add(rasterLayer);
await MyMapView.SetViewpointAsync(new Viewpoint(rasterLayer.FullExtent));
// Populate the combo box. MosaicRulesBox.ItemsSource = _mosaicRules.Keys;
MosaicRulesBox.SelectedIndex = 0;
}
privatevoidMosaicRulesBox_SelectionChanged(object sender, SelectionChangedEventArgs e) {
// Change the mosaic rule used for the image service raster. _imageServiceRaster.MosaicRule = _mosaicRules[MosaicRulesBox.SelectedItem asstring];
}
}
}