Posted on Leave a comment

Lidar & Overlapping UTM Zones

Second zone DEM imported

by Rob Plowright

Intro by Ken: Other than Tasmania & ACT, all states & territories have 2 zones. NZ has just one zone. I recall struggling with marrying datasets from 2 zones for a map that was close to the edge of 54/55. So Rob’s experience will be valuable for the few who are faced with this issue. The general process will also apply to other types of data.

Coping with Australia’s 4 zones

Now that didn’t work

The other day I was doing some virtual exploring: processing lidar in OCAD to see if I could find some interesting terrain. One area I was interested in just happened to be on the boundary between UTM zones 55 and 56; first time I had experienced this. Getting adjacent lidar tiles from different zones to line up in one OCAD file proved to be more difficult than expected. After trying several different approaches and getting nowhere I finally managed to do it, with the help of a suggestion from Ken.

This involved processing the tiles in one zone then using Map > Transform > Change Coordinate System to change the map into the next zone, then processing the remaining tiles. There was one problem however: while the map (contours) transformation went well, the background images (hillshade, vegetation, etc)  did not.

Ken asked me to write-up the process for his up for his blog. Since there was the problem with the background images not transforming properly I sent the first draft to OCAD support. Gian-Reto got right back to me saying that while the method I described would work, there was a quicker way – just using the DEM Wizard. “That’s odd” I thought, “I tried that and it didn’t work”. Gian-Reto soon figured out there was a bug that meant southern hemisphere UTM zones did not process properly and he promptly fixed it.

So just in case anyone wants to know, here is how to do it.

The works

The lidar coverage

I will use an example from Kanangra in the Blue Mountains (not the area I was looking at – which shall remain secret for now).

  • I have five lidar tiles: two in zone 55 and three to the east of that in 56. They are:
    • Taralga201611-LID2-C3-AHD_7746232_55_0002_0002
    • Taralga201611-LID2-C3-AHD_7766232_55_0002_0002
    • Burragorang201805-LID2-C3-AHD_2226232_56_0002_0002
    • Burragorang201805-LID2-C3-AHD_2246232_56_0002_0002
    • Burragorang201805-LID2-C3-AHD_226232_56_0002_0002

As you can see from the double digit components above, the Taralga tiles are in zone 55 and the others in 56

Each tile is 2km x 2km and the numbers after ‘AHD’ give you the grid reference for the SW corner of the tile. So the  SW corner of the first Taralga tile is at 774000 6232000. and the first Burragorang tile is at 222000 6232000  You will notice that the Burragorang tiles have the same northings (6232000) as the Taralga tiles but different eastings.

1. Select co-ordinate system

The area is mostly in Zone 56 so I have decided to make the OCAD file zone 56. Set up a map in zone 56.  First process the zone 55 (Taralga)  tiles. (You could just as easily do zone 56 first).

Select co-ordinate system
Selecting co-ordinate system

The map now looks like this.

Lidar image
Lidar image first zone

Contours (5 and 25m)  are in grey and vegetation height is in the background (I have not bothered rotating the map to magnetic north for this exercise). The blue border shows the OCAD DEM boundary (which is oriented to zone 56)  but I have drawn in the actual boundary of the Taralga tiles’ data with the purple dashes. As you can see the Taralga tiles are sightly rotated relative to the Burragorang tiles, as you would expect since they are oriented to zone 55.

Looking closely
Rotation artifacts

If you look closely there is a little bit of junk in the gaps between the OCAD DEM and the actual (rotated) Taralga tiles.

2. Processing the other zone dataset

Now process the Burragorang tiles – but this time, in the DEM Wizard, make sure it says zone 56 for the DEM tiles.

DEM import next zone
Setting co-ordinate systems for next zone

Now the map looks like this…

Second zone DEM imported
Second zone DEM imported

I have made the Burragorang contours red for the sake of this exercise.

If you look closely at the above image, you can see that there is a large overlap between the westernmost Burragorang tile and the easternmost Taralga tile; almost a whole 2 x 2km tile. It is not always this much. In the area I was looking at before, it was only about 500-600m.

Also in the close-up below, you can see that the red and grey contours  are not exactly the same. This is because the two lidar sets are from different flights: Taralga 2016 and Burragorang 2018. In the other area I was looking at, both lidar sets (zone 55 and 56) were from the same year, and obviously from the same flight, as they matched exactly.

Difference in contours
Close up of difference in contours

The red contours above are more detailed (noisier) as, being more recent, that lidar is higher resolution. If  this map is just for a base map the slightly different contours is not necessarily a problem. But if you want to eliminate the overlapping contours you can crop one set.

3. Eliminate overlap

Since the Burragorang contours are more recent I am going to crop the Taralga contours. Start by hiding the Burragorang (red) contours and draw an area (light blue in this example)  over the parts you want to crop. Then use the Object > crop objects tool. You can also draw the cropping area so as to remove the junk around the edges.

Cropping the overlap
Cropping the overlap

And I get this…

Cropped overlap
Cropped overlap

Unhide the red contours to get this…

The full picture
The full picture

Up close the border between the zones looks like this…

Close up of the join
Close up of the join

Tips

  1. This process, excluding the DEM aspects, can also be used for non-lidar datasets over 2 zones.
  2. If you are new to lidar processing then download one of my DEM templates for use with the DEM Import Wizard. The template has 15 differentially coloured symbols to cover each of the contour selections in the wizard and to avoid confusion with any brown contours in your main or background map. Get one at ocad.com.au/mapping-resources
  3. If you have distortion in a small area, check out Map > Transform > Local transformation. It makes the adjustment of existing maps to geo-referenced base maps (hillshading, orthophotos etc.) easier and more accurate.
Posted on Leave a comment

Downunder Tutorials for Novices & Experts

Tarrawarra map leads OCAD mapping tutorial

How to create high quality orienteering base maps

Preface

This well presented and well illustrated tutorial was prepared by Barry Hanlon of WHO (Western & Hills Orienteers) with contributions from Ian Miller and Janet Morris.

The introduction sets the scene for current mapping. Note that references to OCAD 2018 also apply to OCAD 2019 which under the continued update model is the same product. In the 2020 subscription period, the product will drop the year suffix.

Gathering the data

Here Barry covers data sources and gathering. Some of these are NSW specific but other state equivalents should be readily identifiable by your club’s seasoned mappers. Lidar input is covered as is Kartapullautin.

Creating a base map in OCAD 2018+

Here we have the four key steps. These are followed by a note re use of Kartapullautin to better determine runnability.

Alternative mapping tools

This section covers Open Orienteering Mapper (OOM), OL Laser, LAS Tools and some useful links. Barry does say that if you use current OCAD, you wont need this information. It is great that he has catered for these other orienteering mappers.

Creating base maps with earlier OCAD

Russell Rigby’s Setting up an OCAD base map is just the ticket for mappers who have access to older versions.

More on LiDAR and orienteering mapping

Russel Rigby’s LiDAR for base Maps is a useful complement to Barry’s tutorial and to OCAD’s treatment of the topic.

Off course

Permanent Orieneering Course entry station sign

Finallyyyyy, the entry station sign for the new Eureka Orienteers’ Daylesford VIC permanent orienteering course (POC) was delivered and now erected. ACT orienteers will recognise the style.

This POC is unusual downunder in that users have the choice of participating by way of MOBO mobile app or traditional paper map. MOBO utilises QR codes on posts and was selected because it also provides the opportunity for another QR code on the post to showcase nearby natural or historic mining features in the reserve.

Wesley College, Clunes Campus used the POC 3 times recently (traditional maps) and were delighted with the outcomes for their students. Next year they are looking at a more challenging course for selected students and this will likely be provided via MapRun which doesn’t require fixtures at control sites.

Posted on Leave a comment

OCAD & Mapping Snippets

1915 Vic Geo Survey Dunolly map extract

OCAD reminders

Some tips that tend to be overlooked.lightbulb

40%, 20% discounts ending

And another tip – the big discounts for updating OCAD 12 or 11 to 2018 finish at the end of next month. If you have been thinking about it, I suggest you either do it or diary it.

Team OCAD edition image4 clubs benefit from Team licences

Four clubs have taken advantage of the opportunity to acquire Team licences. In three of those clubs, some club members transferred their licences to the club. Then the club traded each licence in for two Team licences.

Massive savings, significant flexibility. Check out my recent post Hidden Value in OCAD Team Editions for more info.

GIS file conversions

A conversation that crops up more frequently in the lidar era is how to convert a file from one format to another. The FME Integrations Gallery may have the answer for you.

Conversion categories include CAD, GIS & Mapping, Lidar & Point Clouds. The Cloud version appears reasonably priced for say a state orienteering organisation. There is also possibilities for free versions.

Open source PDFsamDocument

Frustrated at the limitations of Adobe Reader and can’t justify Adobe Acrobat? Then take a look at the open source PDFsam.

PDFsam Basic is free and enables split, merge, extract pages, rotate and mix PDF files.  PDFsam Enhanced comes in 3 flavours giving you even more options at a reasonable price.

QuestaBird

Your kids looking for something more to do while waiting for you to finish the course? Or vice versa? QuestaBird is a mobile based adventure game with a purpose. Use your phone to photograph birds, butterflies and moths,  competing with others to collect the most species and the greatest number of animals in your area.

“Players are not only learning about their environment, they’re collecting data that helps protect it.  In effect they have become citizen scientists without even knowing it.”

Andrew Robinson, co-founder of QuestaGame

Downunder geospatial awareness ratingsgeospatial

Australia is ranked 14th and New Zealand 25th in terms of geospatial industry awareness according to Geospatial Media & Communications.

Criteria are data infrastructure, policy framework, institutional capacity, user adoption levels, industry fabric (whatever that means).

The top 10 starts with USA, and apart from Singapore, China and Canada, comprises European countries.

Your dream mapping career?

If you ski you might have seen his work. Jim Niehues, The Man Behind The Map.


The featured image is a very small segment of the 1915 Victorian Geological Survey County of Gladstone map. The detail, drawing and printing is of the highest quality but unfortunately does not show up on this image.

Posted on 1 Comment

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.

Continue reading New OCAD Lidar Features Example

Posted on Leave a comment

Australian Orienteer Summer Edition is Mapped

Geostationary Satellites

Orienteering map technology

The coming edition of the Australian Orienteer carries three articles relating to technology and orienteering maps. Continue reading Australian Orienteer Summer Edition is Mapped