Orienteering NZ Wiki

Imagery, Photogrammetry, LIDAR, Buildings, Kerbs etc. This is WHERE to get data, there may be other topics which discuss using the data. This page covers from 2011, for earlier discussion see Data Sources to 2010

Related categories: DEMs, Google Earth, OCAD - Getting Data In

Hi, I couldn't find 15m DEMs for Whangarei, but had already interpolated 5ms into 20ms, for 300 acres of park-like pine plantation. OCad8. The result seems good enough for a map we'll use once a year. WDC GIS has a systemic shift of about 50metres …contours to cadastral.

After field working 3 contours on a hilltop above the 160m contour, I found a trig, whose height is 180m…very nice

On a small area the human is better than any mathematical interpolation.

New DEM to become available in 2014 http://www.astrium-geo.com/en/168-tandem-x-global-dem

Article on BBC Material World Podcast [19/1/12] http://www.bbc.co.uk/programmes/b019gzqh

1. Looks good. 2. They talk about “customers”.

It is a top of trees DEM because they use radar, which in x-band (the radar wave length they use) don't penetrate vegetation and reflects off the vegetation top. Might be good to know before buying.

Is anyone doing image processing to convert scanned raster images of their fieldwork sketches into vector objects? (I had the impression that OCAD10 can recognise contour lines from scanned maps- might be wrong on that point.)

Haven't heard of anything in OCAD current or proposed. There's other software http://en.wikipedia.org/wiki/Comparison_of_raster_to_vector_conversion_software but how clean is your fieldwork???

Gee you must be a neat (tidy) fieldworker Jason if you want to be able to convert your raster image into vector format. Probably best to manually draw it. That way you can guarantee that what you did out in the field will appear on the final map the way you intended it to be.

I can see it would be of “some” use if you were converting a pre OCAD map into OCAD, but I suspect it would be best to start from scratch and produce a georeferenced map. It will be a great deal more accurate.

Re: Base map contours. For several years in Auckland we have had available Lidar generated contours from the Auckland Council, 1m in rural areas and 0.5m urban. Initially we had to pay for it and it came as georeferenced tiff. Then it became downloadable in small areas from their website as dxf for contours and jpg for photos. And from OCAD10 it could be slotted straight into the map as it came with a georeferencing file. The Woodhill contours provided mixed results; sometimes showing no detail where there were 6m high ridges, but perfect in other places, so I mapped all the the unshown features using the GPS. From last year Council started supplying the files free. Last week I got through to a clued up person in the GIS department who sent my the base data, that's the XYZ (Lat. Long. Elevation)data that was recorded by aircraft. It could be supplied in all sorts of formats, but I took asc, dxf and text for an area of Woodhill of about 10 sq km. OCAD11 Beta (or my computer) couldn't cope with the dxf file which was millions of spot points with the XYZ in text - all georeferenced on the OCAD map. Used the DEM function in OCAD11 (should work in OCAD10 Standard as well)to load in the text file, and also tried the .asc file which was much larger. In both cases my OCAD map now showed elevation as well as NZTM coordinates for where the cursor was located. The rural samples are supposed to be 5m apart and to 0.1m accuracy. But on the map moving the cursor even 2m gave a different elevation to 0.1m accuracy. Then OCAD 10 and 11 can generate it's own contours using the XYZ data. Had some trouble getting this to happen using OCAD11 Beta, I think because I was initially impatient. The asc (continued…)

Re: Base map contours. continued (I inadvertently posted the message) The .asc file had nearly 26 million points, OCAD11 supposedly can handle 25 million. But it went ahead and did the processing anyway. I had asked for 1m contours (to compare with the Council contours) and 5m contours. It took 10-12 hours for OCAD to process and create the contours; it's a reasonably good PC with Quad4 processors and fast video card. But the result is many times more detailed than the Council generated contours, even showing little dots in places. Happily, many of those knolls and depressions that I had previously mapped using the GPS were now showing. I reckon this will make mapping a whole lot easier in the forest. I have asked the nice friendly GIS Council lady to send me more files to cover Woodhill up to and including Rob and Marquit's house, including an experimental urban tree top elevation file in Monte Cecelia Park near home. The first generated 1m contour file in OCAD was 51MB which is using polygon format. So I selected the whole lot and used the ..to Bezier function, took about 1 minute, and exactgly the same lines are now 11 MB. I can perhaps break that down into partial maps for quicker convenient use with a specific map area. Tonight I hope to set OCAD the task of making 2.5m contours for the same area to compare the results. So for any maps you are making in the Auckland Council area, keep in touch, I can possibly help with this data. No doubt there are other Councils out there that have such data stored away. Auckland could also supply in Shape or LAS formats. The zipped file download I got from the Council was 141 MB so fast broadband is a good idea.

Cheers Selwyn, I'm from the Nelson club with access to the Tasman DC data. We currently have Jason Markham doing a map near St Arnaud based on Lidar data and he's recently discovered that at a cost we can potentially source some of the data beyond the Council purchased swaths that were captured when flown. Exciting as we are starting the process of mapping a significant area around the Lake Rotoiti area as a result.

Big files. I got 18gb of contours from a local authority because they were talking about charging for the time to extract stuff, so I asked for “everything”. Took a bit of work with FGIS and QGIS to extract what I wanted.

I think our work is changing from using undermapped photogrammetry (we add extra wiggles in the field) to overmapped LIDAR (we take superfluous wiggles off, by manual tracing, or mathematical smoothing, or whatever).

In the old days, if you weren't perfect (who is?) there might have been missed reentrants. The course planner worked round them, they weren't fatal if you kept controls away from them. In the new way, if you aren't perfect, there are extra reentrants and you may have to look at pretty much everything. There are some papers on the web, I think an IOF Mapping Conference, that talk about the tendency for excessive detaill on maps produced from LIDAR contours.

The significance of Routegadget's experiments, as I understand it, is in applying automated logic to these contours-with-spurious-wiggles to produce something that is like what a good mapper would produce. Is that what he's up to?

If anyone is tempted at some stage I have a Lidar file for the start of Farewell Spit at the very top of the South Island. I may be able to get sufficient info together from my work to put through the programme.

Michael never mind Farewell Spit, can you get Lidar for the top of the Takaka Hill?

No! Not yet. My evil plan of infiltrating the decision making part of the GIS team at my Council is yet to work. Actually, they are doing a fly of all the major rivers with Lidar and I am going to try to convince them to send the plane over Canaan on the way to Golden Bay and hopefully do the Howard Valley near St Arnaud.

On the other hand, have you been to the base of Farewell Spit? I will get a map of there one day. It is a mixture of sand dunes, native forest and strangely shaped hills.

Photogrammetry is coming to an end. Stuart H is among the last of a dying breed. http://www.attackpoint.org/discussionthread.jsp/message_791783#message792118

Can't remember when we were last discussing what's in Koordinates, but it seemed that NZTA had photographed the state highway network over the last few summers. I thought it might be complete, but today I found some SH where they haven't got any. Hopefully they've had planes up this summer filling in the gaps. Anyone found any other new stuff on Koordinates?

Interesting to see what we can learn from the WOC maps. Probably the middle is the toughest test of the detail vs legibility problem - http://www.woc2013.fi/ssl/woc.nsf/0/BF045E63A3EFE6B7C2257BA20042A0C0/$FILE/Middle%20Q%20MEN%201.gif First thing I noticed after reading the ISOM discussion on formlines is, there are a LOT of formlines! Maybe they should have used 2.5m. They have at least made the best of them by dash control, hardly any gaps in places of high curvature. Second is that the rock seems clear, even to the extent that they have been able to also use vegetation boundary dots! Malcolm Ingham's comment may tell us why: “Any rock features shown on the map are really big, meaning that a lot of rock detail of a size that would normally be mapped in New Zealand is not shown.” And they have not resorted to representing the absent rock detail with stony ground dots as the JWOC middle mappers did. Other comments?

G'day

I see that LINZ is making 85% of aerial photography free access. Curious as to whether you know yet whether that is likely to be useful to you or do you have other sources these days? Ken Dowling

Ken, there has been a “club” of mainly govt organisations that has been sharing imagery (the KiwiImage program), and they have now handed this project to LINZ to release on a creative commons basis for the public good. The KiwiImage std I think is 0.6m pixel size and where local authorities have contributed it is smaller, this will be pretty useful. The coverage is shown here: http://www.linz.govt.nz/topography/aerial-images/creative-commons-licenced-imagery

Up till now (and probably still useful until LINZ completes its processing work) methods we have been using include: purchase from aerial mapping companies, buddy-buddy arrangements with councils and other organisations, NZTA has most of the state highway network covered (about a 1km swathe), and the Walking Access Commission has pretty much the whole country covered by www.wams.org.nz.

Although we have been able to BUY aerial photography, and have enjoyed various ad hoc free arrangements, I think the following announcement from LINZ is very significant.

“LINZ has been working towards getting New Zealands most current publicly-owned aerial imagery  covering 95% of the country, freely available to use under an open licence through the LINZ Data Service. Last week, LINZ released all of the North Island aerial imagery on LDS, and will be rolling out imagery for the rest of the country over the coming months.”

LINZ Data Service is at data.linz.govt.nz. The interface looks rather like Koordinates, I think K provides the platform. The images are georeferenced to NZTM which means that they can position themselves automatically in OCAD in version 10 or later. Or to say this in another way, a positioned image may be used to georeference an existing map and identify anomalies - THE most widespread need in orienteering mapping today, I believe.

Another quote: “Almost all data from LDS is provided under the Creative Commons Attribution 3.0 New Zealand licence. This means you are free to use, reuse and share data as long as you attribute the work to LINZ as the original source of the data.” My comment: thanks to all those (including some orienteers) who have worked to make govt agency photography available more widely.

If you have 43min to spare you might be interested in this presentation by the LINZ Data Service: https://www.youtube.com/watch?v=9Pz6QFkAAis I was looking for an indication of when the South Island imagery would become available - they are saying “next couple of months”.

Yes, the LDS video was interesting - I watched it as part of my work. Good news for orienteers with access to free data - completely changed from the dark days.

If anyone has a spare $450 you can get a copy of all imagery in NZ (a couple of terabytes) and you get to keep the hard drives as well.

The rest of the aerial imagery data including layers for the South Island are now available on the LDS. You can view and download the complete dataset here:

https://data.linz.govt.nz/x/vuozYk

From a LINZ newsletter: “We’re about to publish a 1m LiDAR derived DEM and DSM for a large portion of the Auckland region. This data was captured by the Auckland Council, and is part of LINZ’s role in the national coordination of LiDAR data to contribute to the development of a national Digital Elevation Model.”

I would guess this is irrelevant for Auckland mappers who have been able to get data direct from the council, but when it extends across NZ this will be very cool. Though having used a lot of LiDAR derived data, the artificial wiggles have made me appreciate one of the un-sung benefits of Stewart Hyslop photogrammetry. He was a sort of filter of unreasonable detail. Better to add little nooks and crannies in the field than to have to take fictional ones out. I talked to Stewart recently, there's hardly any demand for PG now, but I think he said he could probably get diapositives made if necessary. The old photo library is now being looked after by Opus Consultants in Napier.

Topo Map Extents – relating a map sheet to coordinates

I sometimes want to know what sheet I’m on, eg to home in on the right aerial photos. But LINZ has dropped the table they once had on their website. They’ve sent me the data and I’ve put it up on my website. It’s at www.mapsport.co.nz/topo50mapextents.html. Years ago when they threw the NZMS260 maps away the same thing happened, but I sometimes want photos based on them too. I’ve got those numbers at www.mapsport.co.nz/topo260mapextents.html. If anyone knows another link to this data let us know, it seems crazy that we should have to store it.

I use the following link to find the sheet I'm on: http://www.linz.govt.nz/land/maps/linz-topographic-maps/map-chooser

If you have access to TUMONZ you can use that. The cursor gives sheet number plus co-ordinates

Our President recently came across http://www.arcgis.com/home/gallery.html#c=esri&t=maps&o=modified&a=NZ and brought it to our attention, but on closer examination it was our very own kiwi linz data added to make esri look international. You can find the linz bits and pieces at https://data.linz.govt.nz/data/category/aerial-photos/?page=7. Good to know we are on to it.