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New OCAD Lidar Features Example

Cornish Hill lidar vegetation height image

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:

OCAD 2018 import from ELVIS Lidar image
Mark’s OCAD 2018 import from ELVIS Lidar

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.

I processed the ‘irregular points’ las files through OCAD 2018 DEM import wizard, selecting all options. This provided seven background images such as hill shading, slope gradient and hypsometric shading.

I had selected also;

  • Topographic Position Index (TPI) smoothed contours,
  • depression form lines for both lidar raw contours and TPI generated contours
  • features of small depressions, small knolls and prominent trees.

The processing of an area 1.7 sq.km was just a couple of minutes up to the start of small features processing. The latter took about 10 minutes. (running 64-bit OCAD, 20GB RAM, I7 processor). OCAD help wiki does point out that The function is computationally intensive and may take a while.

The area is the NW part of Cornish Hill which is primarily an old gold mining area. There were ore crushing batteries, tunnel adits, shafts, sluicing … The terrain has plenty of evidence of these activities. The image below;

  • has a grey hill shading base
  • green lines are TPI contours of 2.5m (long dashes), 5m and 25m(index)
  • magenta dots are small knolls
  • magenta circles are prominent trees
  • magenta small depression symbols are hard to spot but many are there
  • the red lines are major depressions

I will be heading out to the area over the next two weeks to closely examine a few small areas. I will report back on the usability of the generated data.

Cornish Hill NW lidar image
Cornish Hill NW lidar image

 

One thought on “New OCAD Lidar Features Example

  1. This is very exciting news.
    Thanks Mark & Ken.
    Time/ Fieldwork saving would expect to be extreme.
    But…..20gb of RAM, Wow that’s some PC!
    cheers
    Mike

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