You say you cannot add a second DEM to the first one. Can you load that second DEM alone? How big is each of them now? I understand your merged quite a few of your smaller ones into a bigger one. All .dem files saved by TransDEM are UTM/WGS84 and allocated to an UTM zone. Are both DEMs in question in the same UTM zone?
A merge operation will allocate lots of additional memory for temporary use. With very large DEMs this can easily exceed available main memory, even on systems that have are reasonably equipped. I managed to exhaust the 64GB I have on my current system.
Aprinto wrote:
My country, Indonesia had GEOTIFF 0.27sec arc with vertical datum EGM2008 and in few months will upgraded to EGM2020. But because TRANSDEM didn't accept EGM2008. I start to convert it to WGS84 via QGIS then converted to DEM via TRANSDEM 2.6.6 then try it.
For TransDEM purposes, the EGM doesn't really matter, we are not that accurate here
. However, reference ellipsoids and datums, based on newer EGMs, tend to get new EPSG codes. TransDEM defines several EPSG codes as "aliases" to be mapped to WGS84, but certainly not every possible one. Can you point me to your geo data source - I guess data is publicly available and free of charge? - and to information of the underlying spatial reference system?
TransDEM has quite a few users in Indonesia and direct support for Indonesian geo data might be welcome.