ArcGIS Pro Tutorial: Mosaic Multiple DEM to New Raster in ArcGIS Pro | Merge Raster Data | Mosaic Multiple DEM data

ArcGIS Pro Tutorial: Mosaic Multiple DEM to New Raster

Working with digital elevation models (DEM) often requires combining multiple raster datasets into a single seamless surface. This comprehensive tutorial will guide you through the process of mosaicking multiple DEM datasets in ArcGIS Pro to create a unified raster dataset.

Understanding Raster Mosaicking

Raster mosaicking is the process of combining multiple raster datasets into a single, seamless raster. This technique is essential when working with large geographic areas that span multiple DEM tiles or when integrating data from different sources.

Prerequisites

• ArcGIS Pro installed and licensed
• Multiple DEM raster datasets
• Sufficient storage space for output raster
• Basic understanding of raster data concepts

Step-by-Step Process

Step 1: Prepare Your Data

Before starting the mosaicking process, ensure all your DEM datasets are properly organized:

1. Verify that all DEM files are in compatible formats (GeoTIFF, IMG, etc.)
2. Check that coordinate systems match across all datasets
3. Ensure consistent cell sizes for optimal results
4. Organize files in a single folder for easy access

Step 2: Add Data to ArcGIS Pro

1. Open ArcGIS Pro and create a new project or open an existing one
2. Click on the “Map” tab in the ribbon
3. Select “Add Data” from the Map tab
4. Browse to your DEM folder and select all raster files
5. Click “OK” to add the datasets to your map

Step 3: Access the Mosaic Tool

1. Navigate to the “Analysis” tab in the ribbon
2. Click on “Tools” to open the Geoprocessing pane
3. In the search box, type “Mosaic”
4. Select “Mosaic” from the search results (Spatial Analyst Tools > Raster > Mosaic)

Step 4: Configure Mosaic Parameters

In the Mosaic tool dialog, configure the following parameters:

• Input Rasters: Add all your DEM datasets by clicking the folder icon and selecting multiple files
• Output Raster Dataset: Specify the location and name for your output mosaic
• Pixel Type: Choose appropriate pixel type (typically 32_BIT_FLOAT for DEM data)
• Method: Select how overlapping areas will be handled:
  • LAST – Uses the last raster’s pixel values
  • FIRST – Uses the first raster’s pixel values
  • BLEND – Blends overlapping pixel values
  • MEAN – Calculates the mean of overlapping pixels
• Mosaic Colormap Mode: Choose appropriate colormap handling

Step 5: Execute the Mosaic Process

1. Review all parameters to ensure they’re correctly set
2. Click “Run” to start the mosaicking process
3. Monitor the progress in the Geoprocessing pane
4. Check for any warning or error messages

Step 6: Verify Results

After the process completes:

1. Add the output raster to your map
2. Check visual continuity across the mosaicked area
3. Verify elevation values are consistent
4. Examine overlapping areas for any artifacts

Advanced Mosaicking Options

Using Mosaic Dataset Approach

For more complex scenarios, consider using a Mosaic Dataset:

1. In the Catalog pane, right-click on a geodatabase
2. Select “New” > “Mosaic Dataset”
3. Specify name and coordinate system
4. Add rasters to the mosaic dataset using “Add Rasters”
5. Build overviews for better performance

Handling Different Coordinate Systems

If your DEMs are in different coordinate systems:

1. Project all DEMs to a common coordinate system before mosaicking
2. Use the “Project Raster” tool for individual datasets
3. Ensure all datasets use the same datum and projection

Quality Control Techniques

• Use the “Check Geometry” tool to identify issues
• Apply “Fill” tool to correct gaps or NoData areas
• Use “Clip” tool to define boundaries if needed
• Apply smoothing filters to reduce edge artifacts

Performance Tips

• Ensure adequate RAM for large datasets
• Use SSD storage for faster processing
• Consider processing in chunks for very large areas
• Close unnecessary applications to free up resources
• Use appropriate output formats (GeoTIFF with compression recommended)

Common Issues and Solutions

• NoData gaps: Use interpolation or fill tools
• Seams between datasets: Adjust mosaic method or apply blending
• Performance issues: Reduce resolution temporarily or process in sections
• Coordinate system conflicts: Standardize all inputs before mosaicking

Frequently Asked Questions