ELVIS LiDAR and OCAD
The ELVIS output format Esri Ascii Grid, can be imported directly into OCAD 12 via the Import Wizard in the DEM menu. So you not only have an easy way of obtaining the data, you also have an easy way of using it. (See my earlier post ELVIS rocks with LiDAR contours on the basics of using ELVIS).
ELVIS LiDAR vs state geospatial vector contours
For a small area of Anglesea used in 2015 for a mountain bike orienteering event, I downloaded ELVIS LiDAR and VicMap vector contours. Then overlaid them in OCAD.
The brown contours are VicMap 10m obtained via download of vector form via Shape file. 25m index contours were also obtained but do not appear in this fragment.
The other 3 colours are from ELVIS LiDAR data;
- grey is 1m (shown only in second image)
- green is 5m
- purple is 25m index contour
At first glance there is a general consistency if we ignore the many minor indentations in the LiDAR lines that could be easily smoothed in OCAD.
However the 1m LiDAR does indicate the existence of two lower parts of gullies that are shown in the VicMap contours, albeit the eastern displaced. So maybe 1m contours could usefully inform the mapper at draft stage in some map areas.
LiDAR contours smoothed via Karttapullauten
Karttapullauten generates orienteering training maps from LiDAR data.
This is similar to the result when smoothing in OCAD except that Karttapullauten has interpolated 2.5m contours (the dashed lines). Interestingly, this makes the progression of the above mentioned eastern gully much easier to observe.
Using ELVIS DEM data in OCAD
There are 4 video tutorials on DEM at http://ocad.com/en/support/learn-video. These videos are useful for OCAD 10, 11 and 12 users.
I created a 4 minute video tutorial on the basics of using ELVIS. View it online at www.screencast.com/t/y3MTbMzzO
Following on from that is a 4 minute video of importing lidar data via the DEM import wizard. It is one of OCAD Inc’s video tutorials – DEM Wizard – contours
Users of OCAD 10 and 11 don’t have the wizard but should be able to interpret the wizard settings.
I created an OCAD template for importing the DEM data and creating the various contour styles. This file can then be imported into your OCAD map file without overwriting any existing brown contours. Head to my resources page for those.
- When you download ELVIS data, it is the .asc file that OCAD DEM import wants,not the Shape file.
- If you get nothing showing after import, then check the .asc file content. You can use any text editor to read it. In the header lines there is a value for NODATA. If the file is composed completely of that value then there is no LiDAR data for the area you selected. ELVIS now warns you if there is no data in the selected area.
- When you are asked which co-ordinate set you wish to use, unless you have set up your OCAD file to match the location of the imported DEM data, then select the upper set which is that of the DEM data. Else the DEM data will likely be located far beyond the reach of your OCAD map area.
- If you expect to frequently use LiDAR data, then importing into a special OCAD file can be a boon, It should be empty and have just essential symbols that don’t clash with standard symbols for when you import that OCAD file into your working file. Such a template is downloadable from the section immediately above.