What's the best way to build a mosaic of elevation data (from several .img files)?

Question

My ultimate goal is to create a DEM of a large portion of land (spanning multiple counties) in New York, using thousands of .img files that cover my Area of Interest. With very limited experience with this, my question is: What is the very best way to go about this?

If I were to guess, I would say the best way would be to create a mosaic dataset, and add all the individual .img files to it, correct? But I know mosaic datasets can get complex, so what are some of the finer details I should be concerned with?

A few specifics:

* The .img files are a mixture of 1-meter and 2-meter resolutions
* My final DEM will need to be projected  in State Plane NY East
* Currently, pixel values are in meters, but will want them in feet        
* Each .img files is about 9 MB

Any and all feedback/references (i.e., videos, articles, or any type of instruction/guidance) are welcome . Let me know if more information is needed.

Thank you!

RedfredGarett · Answer

If you're creating a mosaic dataset with your elevation data, you can add the lidar data. This data can be combined with other elevation data, such as SRTM or NED raster data sources. Lidar data can be managed within a mosaic dataset by adding the LAS files, LAS datasets, or terrain dataset. For example, you can add all your LAS files, from all your different acquisitions, and use the mosaic dataset as the single source for finding the data as it's needed.

Using the mosaic dataset, you can also serve the lidar data as an image service providing access to the interpolated surface, or even to allow users to download the source files

Steps to add lidar data to a mosaic Dataset

* First create a mosaic dataset with the Create Mosaic Dataset tool.
* In the Catalog window or ArcCatalog, right-click the mosaic dataset and click Add Rasters. The Add Rasters To Mosaic Dataset tool opens.

3. Click the Raster Type drop-down list and click one of the following:

* LAS
* LAS Dataset
* Terrain

There are properties that need to be set when using either of these raster types, therefore, you cannot run this tool without setting those properties.

4. Click the Edit Raster Type Properties button Properties.
5. Click one of the following tabs, depending on the raster type you chose:

*     LAS
*   Las Dataset
*    Terrain

You will likely want to modify many of these parameters. To learn about each of the parameters on this tab, see either:

*     LAS To Raster function
*    LAS Dataset To Raster function
*   Terrain To Raster function

6. You can accept all the defaults, but you must enter a Pixel size.

7.  If the pixel size is 3-4 times larger than the average point distance, you can safely use binning. If the cell size is smaller than that, you can try binning with void filling turned off. If the resulting raster mainly contains voids and only a few single data cells, binning generally does not produce a meaningful elevation raster.

8. If you're adding LAS files, you may want to check Treat each folder as a dataset. This will add all the files in a folder as a single item in the mosaic dataset, which is more efficient for the mosaic dataset. You may choose to check this option if all the LAS files in a folder belong together and have the same spatial reference.

9. You may want to modify the Cache folder and Number of cached surfaces as they will take some space on disk and need to be moved with the mosaic dataset if it's moved.

10. Once you have set all the properties on this tab, you can close the dialog box by clicking OK.
If you won't be adding more data to the mosaic dataset, you may want to check Update Overviews.

11. If you won't be adding more data to the mosaic dataset, you may want to check Update Overviews.

12. If the coordinate system for the data isn't the same as the mosaic dataset, expand the Advanced Options, click the Coordinate System for Input Data button Properties and select a coordinate system.

13. Click OK.

Now you can view the mosaic dataset in ArcMap, ArcGlobe, or ArcCatalog. Remember, the cache is created the first time the dataset is drawn; therefore, it will take some time before the surface can be viewed.

DanPatterson_Retired · Answer

I will start with the help topic, which is comprehensive and probably seen What is a mosaic dataset?—Help | ArcGIS for Desktop