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Trig points

Posted: 27 February 17 12:35 pm
by Bristag
Hi All,
I would like to query about Trig points

Q1 how has GCA determined which ones to publish as there seems to be many more all over the place?
Q2 From my research there doesn't seem to be much of a difference between a trigpoint and an survey marker and even a benchmark they are all geodetic markers, it seems its just the accuracy that's involved to what type it is. Can I find and publish more of these types of geodetic markers as trig caches?

Thanks

Re: Trig points

Posted: 27 February 17 1:01 pm
by caughtatwork
1. We took all the data we could from Geoscience Australia and published what they had in their list. Since then additional TP's have been located and published and some has been archived as being on private property.

2. TrigPoints are Trigonometrical Stations of Type = Horizontal Control Pointand not survey marks. They serve a different purpose and we don't publish SM's as TrigPoints. TP's do not cover all geodetic markers which is why TP's are only Trigonomtrical Stations. There may be some rogue TP's listed, but not too many and if they're identified they're generally archived.

Re: Trig points

Posted: 27 February 17 8:08 pm
by Richary
There are also generally locationless caches available where you can log finds for the various state survey markers.

Re: Trig points

Posted: 27 February 17 9:45 pm
by Bristag
Thanks for the reply.

I am now wondering how does one tell the difference between a survey marker and a trig point. I have found a few GCA trigs and most don't have a tripod frame ect. Its generally a disk thing mounted in concrete, which I always assumed was a survey marker.

I found this https://www2.landgate.wa.gov.au/Gola/go ... tNo=100501 the other day and listed it as a trig cache but now i'm not sure i did the right thing.

I have read that benchmarks are controlled both horizontally and vertically, and I realised the other day that the USA has a whole benchmark section to the GC site, why not list benchmarks in GCA?

Regards

Re: Trig points

Posted: 27 February 17 9:53 pm
by Bristag

Re: Trig points

Posted: 27 February 17 9:59 pm
by Bristag
This will be of interest for anyone looking to find standard survey marks in western australia, it shows accuracy and type (benchmark or not) although it doesn't seem to show which ones are associated with a Trig tower or the like

https://www0.landgate.wa.gov.au/__data/ ... -Atlas.pdf

Re: Trig points

Posted: 28 February 17 12:09 pm
by Chwiliwr
In WA the best way to see if any of the SSM points are trig points is to see if it is marked as such on a topographical map. (I use the Oziexplorer WA topo maps of various scales 1:250,000 down to 1:25,000.)

I have found a lot of SSM plates without structures that I thought may have once been a trig but have never added them unless I confirmed on a topographical map that it was marked as a trig on them.

Some of the other WA cachers are not so careful so some SSM without structures have been added that are not really a trig point and are not marked as such on any of the various scale topographical maps.

This information is now a few years old so may be out of date now but Landgate advised when I was working with them on another project that they cannot tell directly from their database what is a trig and what is not. They have to manually look up 'survey books'?? to find out. In their database trig points and the SSM points carry the same code. I confirmed this as I had a copy of their database at the time and checked for the difference on GCA recorded trigs and other SSM marks and found no difference in the codes for them.

If you want to check if a point is a trig or not and cannot do it yourself send me the coordinates and I will look at the maps and see for you.

Re: Trig points

Posted: 01 March 17 5:25 pm
by Bristag
Hi
Thanks for the info and offer, I had noticed the lack of Trig sites in the Northam area and wanted to add to the map. I knew of the two I published recently hence why I did before realizing that it wasn't the intention for 'Trig' caches.
I have since found some other SSM's in the area but they aren't in places worthy of a cache.

Re: Trig points

Posted: 01 March 17 8:16 pm
by Chwiliwr
Bristag wrote:Hi
Thanks for the info and offer, I had noticed the lack of Trig sites in the Northam area and wanted to add to the map. I knew of the two I published recently hence why I did before realizing that it wasn't the intention for 'Trig' caches.
I have since found some other SSM's in the area but they aren't in places worthy of a cache.
I've put a NA on one of trig points you added as it is just a SSM and was never designated as a trig. I found that one ages ago but was disappointed it wasn't one.

The other one on Bobakine hill is marked as a trig on the 1:100K topographical map and also on the 1:50K topographical map.

With the lack of trig points close to Northam it may be that they are on private property or surrounded by private property so are not available. (Quite a few of WA trig points are on private property.) When they are found to be not accessible like that they are archived so do not appear if you just look at the active ones.

Re: Trig points

Posted: 01 March 17 8:48 pm
by caughtatwork
BTW. As community assets you can have them archived yourself by logging an archived log against the cache and giving the reason. It works exactly the same as if you owned them yourself.

Re: Trig points

Posted: 01 March 17 10:53 pm
by Bristag
Thanks for checking Chwiliwr, I have archived it, I do agree it is a shame it wasn't one though.

Re: Trig points

Posted: 01 March 17 10:57 pm
by Now_To_Morrow
caughtatwork wrote:BTW. As community assets you can have them archived yourself by logging an archived log against the cache and giving the reason. It works exactly the same as if you owned them yourself.
This is good news. I can clean up my area map of private property trigs now. They've been taunting me.

Re: Trig points

Posted: 02 March 17 8:13 am
by caughtatwork
That's always been the case, since the day they were introduced. http://wiki.geocaching.com.au/wiki/Trigpoint#Archiving

Re: Trig points

Posted: 26 March 17 9:07 am
by nutwood
Is it mandatory to archive trigs on private property? I would think the majority of trigs in rural areas are on private property but sometimes it's tricky to tell. I've logged them where I've gone and banged on a farmers door to gain access. The trig itself might not be on private land but if it's landlocked by private property, it might as well be. I've never even considered archiving one.

Re: Trig points

Posted: 26 March 17 12:04 pm
by caughtatwork
Mandatory? No. As in if you see one on private property do you HAVE to archived it? No. Should you, well I think so. There's no point in taunting people with TP's that cannot be visited. On the other hand, if you have gained access with permission then please UPDATE the cache description (everyone can update a TP), with that information so the next finder knows what to do.