ELVIS lidar data processed through OCAD 2018 DEM import
Mark Roberts recently reported
Just a note that I recently downloaded some lidar data from ELVIS and imported to OCAD 2018 and the results are spectacularly good. The vegetation height function depicts clearings and buildings perfectly:
Mark later remarked that lidar is becoming very readily available and the OCAD processing of lidar is so easy.
VIC lidar data processed through OCAD 2018 DEM import
Following Mark’s report I received ordered lidar data for a permanent orienteering course in Daylesford, VIC. Here in VIC we do not yet have free access, however on behalf of Orienteering Victoria I have established a protocol with DELWP for access to lidar data. As their paid orders take priority it takes some weeks to fulfill an order but the wait is certainly worthwhile.
This is not to claim that making orienteering maps is boring, as one dictionary suggests that a drone is “A person who does tedious or menial work; a drudge” ….. on the contrary, anyone who knows me will know that I find the work stimulating and rewarding, and certainly not menial. Indeed making orienteering maps is one of my passions in life, and another (there are more!) is the theory of flight Continue reading A Drone Goes Orienteering Mapping
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.
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.
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.