Freitag, 24. Mai 2013

Mappers Blog: To the island

fig.1. Basemap for the Fjärdlång Project.

Tomorrow I leave for my next project, a map of Fjärdlång, a island of Stockholm Skärgården. The island has never been mapped before (for orienteering). Figure 1 shows the basemap I will use. It is based on the swedish kind of laser data (including also information on vegetation height). It consists in 0.5m contours, rock cliffs as the "intensity"-view, post-processed with Photoshop basically showing areas with trees in white and without trees in yellow. The data processing I made with OLaser. Above that a regular mesh as the magnetic north lines which in Sweden are not parallel to the maps edge (in contrary to Norway or Switzerland).

Besides I calculated a base map with karttapullautin, which in contrary to OLaser does some interpreting/generalization of the laser-data. I plan to interpret myself frist, then I will look at the automatically achieved result...

Kommentare:

Alex hat gesagt…

aus Neugier:
Könntest du kurz erklären wie man mit Hilfe von Kartapullautin und Schweizer DOM- und DTM-Files eine Karte erstellt?

M.Lerjen hat gesagt…

Hi Alex, today I would say, that there is no way to use Karttapullautin with the data provided by the Swiss Authorities.
The basic problem is that Swiss DOM and DTM (now Alti3d) both are only and partly modified extracts of the laser-measurement while the las 1.2 format provided in Finland and Sweden (see description in swedish) is pretty much the complete and raw information collected at a laser session combined some additional classification (f.ex. water surface, bridges a.s.o.). This data format includes the entire response (treetops to ground) opening to broad variety of perspectives as for example the height of the vegetation layer or the object intensity (as on the sample above) which enables an easy distinction between coniferes and decidouos trees.
Karttapullatin as OL-Lasers strength only shows when working with this las format. Alas!

Alex hat gesagt…

thank you!

Divya hat gesagt…

Your blog is good.