Function Description

Manage Mosaic Dataset of images can be regarded as the process of image warehousing, which is to add images to Mosaic Dataset, and multiple images in different formats (.tif.tiff.img) can be added to the same Mosaic Dataset. And a large numb of images can be adde at a time.

Storage is efficient because Mosaic Dataset does not copy the original image file, but records the path, contour, resolution and other meta-information of the image.

Data Preparation

Before storage, you first need to understand the basic information of the images to be stored, including the size of Image Files, the number of files, whether the pyramid has been established, and other information, so as to make adequate preparations for image storage.

• Image Files size and number of files can be used to estimate the time and disk space required for image storage operations. The following is the reference provided by the test results. Global DEM Data with a resolution of 30 meters, with a 22667 of 0.98 TB. It takes 14 minutes to Add all to Mosaic Dataset in UDBDatasource. After adding, the UDB file is 16 MB and the udd file is 22 MB.
• Whether the pyramid is created for the image and whether the image is stored in blocks can significantly improve the display efficiency of the image. The construction of Image Pyramid and the conversion of the image into block storage can be completed before or after the storage.
• Image pyramid construction and block storage conversion, as well as post-image Map Cache generation, all support multiple processes. Therefore, in order to achieve higher execution efficiency, a machine with higher configuration can be prepared to perform these operations.
• The above mainly considers various resources required for image storage. You also need to know the image itself. Whether the content recorded by the image is the pop reflection of the ground object or the elevation involves which display method is used for the image Map in the later stage. For example, for DEM Data, the elevation classification can be displayed through the color table and the three-dimensional shading effect.
• View the Image Projection : In the Build Mosaic Dataset, in order to make the image mosaic display efficiently and correctly under the Target Coordinate System, First, You need to know the coordinate information of Image Files (directly open Image Files in the Open File Datasource mode, and you can query the coordinate system information in the Dataset Properties information). And determine the coordinate system required for Mosaic DatasetShow in Map, for example, Image Files itself is China2000 zonal projection, the coordinate system for map display needs to be China2000, and the coordinate system for actual map display may be inconsistent with the Image Files coordinate system. The following describes how to set the appropriate coordinate system for Mosaic Dataset from the original Image Files with and without coordinate system:
  1. When the original Image Files has a coordinate system and is inconsistent with the coordinate system required for map display, it is recommended to set the Coordinate System Settings of Mosaic Dataset as the coordinate system required for map display.

     For example, the image Original Coordinate System is China2000 zonal projection, the coordinate system required for map display is China2000, and the coordinate system for Build Mosaic Dataset is set to China2000. Because the map will automatically convert the image from China2000 Projected Coordinate System to China2000 coordinate system when it is displayed, users do not need to do additional coordinate system processing. Compared with setting the Mosaic Dataset as the China2000 zoning Projected Coordinate System with the same coordinates as the Original Image, and then setting the map Dynamic Projection as China2000 during display, The former way shows higher efficiency. Therefore, it is not recommended to use Dynamic Projection for maps when using Mosaic Dataset.

  2. When the original Image Files has a coordinate system and is consistent with the coordinate system required for map display, it is recommended to set the Coordinate System Settings of Mosaic Dataset as the coordinate system required for map display.
  3. When the original Image Files has no coordinate system (Planar Coordinate System) but the coordinate system of the data is known to the user, there are the following handling methods:

     (1) Do not process the original Image Files, and set the Coordinate System Settings of Mosaic Dataset as the coordinate system of the data. In this case, the map Display Coordinates must be consistent with the data coordinate system. For example, Original Image has no coordinate system (Planar Coordinate System), but the user knows that the data is China2000 zonal projection. Then the Coordinate System Settings of Mosaic Dataset is projected as China2000. In subsequent use, the coordinate system displayed on the map must also be China2000 zonal projection, and the map cannot use the Dynamic Projection function. Because the original Image Files lacks a coordinate system, the automatic Projection Transformation cannot be performed inside the program, and the image cannot be displayed normally.

     (2) Give the data Coordinate System Settings known by the user to the original Image Files, that is, process the original Image Files into the case with a coordinate system. Refer to 1 and 2 for Coordinate System Settings for subsequent Mosaic Dataset.

Function entrance

• Start tab-> Create Dataset drop-down box-> Raster/Image/Video-> Tessellation.
• Toolbox-> Image Management-> Build Mosaic Dataset-> Build Mosaic Dataset.

Parameter Description

The clipping shape of each image is a face object and is separately stored in a shapefile file. The File Name is the same as the Image File Name. The *.shp File must be stored in the same level directory of the corresponding Image Files. See the Crop Display Method for a more detailed description of the clipping file.

1. You can add and delete Image Files through the tool in the toolbar. Mosaic Dataset will record the absolute path information of Add image file.
   • Add: Add Drop-down Button contains the following addition options:
     • Add File: Adds the specified Image Files (*.img, *.tif, *.tiff, etc.) to the current list area. Support adding *.tif, *.tiff, *.imgImage Files in Cloud Storage.
     • Add Folder: Add all Image Files under the specified folder. When Add image file by means of Add Folder, Uniform Settings can be set for the Search files in subfolders of Image Files. Image File Types supported to be added include: IMG File, TIFF File, ECW File and SID File. Support for adding folder paths in Cloud Storage.
     • Add List: Add the specified list file (*.txt, *.tif, *.tiff, etc.), and the program will add all the images it contains to the current list area according to the list information. The path information of Image Files in Cloud Storage can be written in the manifest file *.txt, and the path format is://minio @ image/ChinaPart1/H47C001004.tif, Refer to Cloud Storage for detailed instructions.
     • Add Mosaic Data: Add the image information in the existing Mosaic Data? Get Data set.
     • Add FTP Address: Add the FTP server path to obtain the Image Files in the FTP server.
   • Delete: Delete images that do not need to be added to Mosaic Dataset.
   • The child Dataset List area displays the Basic Info of the added child Dataset, including:
     • Alias: The name of the child Dataset as it will appear in this collection when added to the Image Dataset Collection.
     • Path: Displays the disk path where Image Files is located.
2. Set the Datasource and Dataset Name where the Mosaic Dataset is stored.
3. Uncheck the Add Clip File: check box to crop the active area of the displayed image with the help of the Mosaic Dataset crop child Dataset. It is often used in Image Data to cause deformation after Projection Transformation, and to deal with the area without value by clipping the reference data set. The reference file is *.shp format data. If there is a corresponding *.shp File in the Image Files folder, check this box, otherwise the program calls the Footprint Data of each image as Clip Bounds by default.
4. Set the Target Coordinate System. After the Add image file, Application will set the Coordinate System Settings of the first file with a coordinate system to be added as the coordinate system of the current Mosaic Dataset. At the same time, Reset Coordinate System and Copy Coordinate System in the Coordinate System Settings toolbar are supported. Set Coordinate System in three ways such as Import Coordinate System. Refer to the View the Image Projection for the Mosaic Dataset coordinate system settings.
5. Click the Run button to complete the creation of the Mosaic Dataset. Add the nodes of the created Mosaic Dataset under the Workspace ManagerData source node, which are Outline, Boundary and Clipping.
   • Contour is the basis for Mosaic Dataset to store and organize Image Files. It is a Region Dataset, and each face object is the Geographic Range of a single image, as shown in the following figure. The distribution and coverage of the image can be viewed globally through the outline.

     Figure: Global's 30m resolution DEM Data (Mosaic Dataset Profile)

     In addition to the Geographic Range, the outline also manages meta-information such as the storage location of each Image File and the maximum and minimum resolutions of the pyramid, as shown in the following figure. In practical applications, the contour may also need to manage other information of the image, such as the shooting time of each image, the manufacturer, etc., which can be achieved by creating user fields and updating the fields.

     Figure: Profile Dataset Properties Table

   • Boundary is the Region Dataset, in which the face object can be used to set the Visible Bounds of Mosaic Dataset. It is built based on the contour by default; You can also use Custom Bounds or the specified GeometryRebuild Boundary to make the Mosaic Dataset display the image within the boundary according to the new boundary.
   • Clipping is Region Dataset, in which the object is the Visible Bounds controlling each image. It is generated based on the clipping file selected during Build Mosaic Dataset. If there is no separate clipping file, it is created based on the image outline by default.
6. In Layer Manager, a Mosaic Dataset consists of four parts: a boundary line, a callout, an outline, and an image. As shown in the figure below, the Mosaic Dataset contains 6 Image Datasets, which are displayed in the Map. The pink wireframe is the boundary line, the green line is the contour line, and the bottom is the image Dataset displayed in the mosaic.

   Figure: Mosaic Dataset Structure

   • Contour: The image contour is based on the spatial reference of the Mosaic Dataset, which reflects the real boundary of the image in the Mosaic Dataset.
   • Boundary line: It is constructed based on the image contour line. You can dynamically change the overall display of the Mosaic Dataset by adjusting the Boundary line range. Under specific requirements, the original Mosaic Dataset boundaries can be replaced with existing vector boundaries or administrative divisions to change the data display.
   • Image: Add all images managed in Mosaic Dataset and display them together dynamically.
   • Annotation: File Name added to each Original Image in Mosaic Dataset.

Related topics

Overview of Mosaic Dataset

Mosaic Dataset Display