Why do I get an error that says “not enough disk space available” during processing in ERDAS IMAGINE when I have plenty of disk space?
ERDAS IMAGINE is not memory intensive (except in the 3D environment), but it is temp-space-intensive. Many common remote sensing tasks, particularly mosaicking, layer stack, resolution merge, and rectification use a lot of temporary space. In mosaicking, for example, ERDAS IMAGINE is taking all of the images and performing numerous intermediate calculations on the entire dataset in order to stitch the scenes together. We recommend that a user have available temp space of at least 2.5 times the total combined files sizes of all the input images. For example, a mosaic of ten images totaling 100 MB might need a minimum of 250 MB of free temp space to run efficiently.
To check this in ERDAS IMAGINE, open the Preference Editor (File tab > Preferences) and select the User Interface && Session category. About halfway down there is a setting for the location of the Temporary File Directory. It is critical that this be set to an area where there is sufficient free disk space. Total free space on a hard drive is not what is important. It is important that the space be available to the temp space setting. This is often set to C:\, or the default setting of $TEMP which is C:/Documents and Setting/Username/Temp. There often is not be enough space in these locations. If you have a large empty network drive available, that may work better. We generally say that a local drive is better for temp space (to avoid packets getting lost), but a network drive can work. Tip: Be sure to set your external drives to NEVER Sleep if you plan to use them for temp space with Mosaic. The default sleep setting is usually fifteen minutes which could cause a problem for really large outputs.
You may have better success by running a series of smaller mosaics and then mosaicking them together to produce your large output mosaic. This can significantly reduce the overall number of seamlines and feathering zones and the attendant intermediate calculations that have to be performed to a more manageable level.
Keep in mind that if you are using compressed data such as MrSID, the problem can be severely compounded. To perform any processes in ERDAS IMAGINE with compressed images, the images must be uncompressed first. In the scenario with MrSID, at 20-to-1 compression, you could be looking at extraordinary data size, enough to freeze almost any computer.