hi what can i do for define system of projecion coordinative of dtm on arcgsi 10.1
What format is your dtm in? If it is a raster, you could apply the Project Raster tool.
Grid files should still be able to be reprojected using the Project Raster tool. At least in 10.3 and later. I can't find documentation on 10.1, but I would assume this is still supported.
ok I am trying hope to function on arcgis 10.1