Nowadays is very common to obtain spatial information using global digital models obtained
by RADAR techniques in campaigns carried out by governmental organisations which
put them at public’s disposal in Internet. The resolution of these models is very variable,
oscillating from 5’ to 30” of arc, but we can find them much denser, like SRTM which allow
to have, in function of the geographical location, a resolution between 30m and 90m. These
models can be useful to get to small and medium scale ortophotomap, with enough
accuracy to work in cartography, and engineering projects, saving money and time in the
producing process.