What is a trig?

[agentmancuso]

Thanks Ed, I don't think I'd ever noticed your log before, or if so I'd managed to forget all about it. I guess I assumed that the variation in co-ords was generally due to improvements in the accuracy of surveying techniques.

[peregrinus]

I've just logged a visit to Windsor Castle (the castle not the FBM)
http://trigpointing.uk/trig/23617

It was down as a destroyed bolt. Since the centre and flagstaff are still there I've logged it (under admin) as Good and changed from Bolt to Intersected Station.

Is this an OK way forward? Alternative is to add the IS as a new trig (same station)

Rob

[agentmancuso]

I've just logged a visit to Windsor Castle (the castle not the FBM)
http://trigpointing.uk/trig/23617

It was down as a destroyed bolt. Since the centre and flagstaff are still there I've logged it (under admin) as Good and changed from Bolt to Intersected Station.

Is this an OK way forward? Alternative is to add the IS as a new trig (same station)

Rob

I'd probably have done the same Rob: normally a definite sighting of a physical station would take precedence over an intersection, but I guess 'continued existence' has to take precedence over 'dearly departed'.

[Teasel]

I've just logged a visit to Windsor Castle (the castle not the FBM)
Is this an OK way forward?
Rob

I'd have done the same, but I don't really think it's an OK way forward. To those who have a mental heirarchy of the "worthiness" of trigs, the bolt is more worthy. They may filter out intersections completely, yet this "Good" condition will still show up on their lists. And to those of us with borderline OCD, the idea of having a single condition for three separate entities is just wrong! I'm aiming to create a trig record for each mark, not station; ideally without upsetting people who want to see all the marks and logs together in one place. I'm not sure how the GUI should work, but I'm pretty clear that separating by mark is the only way that the underlying database can make sense.

On a related note, please can someone explain to me what a "centre" is? The Windsor Castle centre coordinates are only about 3cm from the Flagstaff coordinates.

[peregrinus]

I've just logged a visit to Windsor Castle (the castle not the FBM)
Is this an OK way forward?
Rob

I'd have done the same, but I don't really think it's an OK way forward. To those who have a mental heirarchy of the "worthiness" of trigs, the bolt is more worthy. They may filter out intersections completely, yet this "Good" condition will still show up on their lists. And to those of us with borderline OCD, the idea of having a single condition for three separate entities is just wrong! I'm aiming to create a trig record for each mark, not station; ideally without upsetting people who want to see all the marks and logs together in one place. I'm not sure how the GUI should work, but I'm pretty clear that separating by mark is the only way that the underlying database can make sense.

So it would be better to add the IS as a separate trig and leave the Bolt as is. I'll do so.

On a related note, please can someone explain to me what a "centre" is? The Windsor Castle centre coordinates are only about 3cm from the Flagstaff coordinates.

Would they have measured the turret while they were up there, established the centre and measured its position relative to the bolt? Just a guess.

[peregrinus]

Similar issue with Meppershall Ch Twr which is on as an Old Trig, type=Pillar
I've now added the IS as a separate trig called Meppershall Ch Twr - VANE http://trigpointing.uk/trig/25654
Is this the way to go? I was lazy the other day and just logged it as good with an explanatory note in the log.

Is "Pillar" the right Type for Old Trigs, though?

Also how does the Status field work? (Visible only to admins in edit mode)

Finally I notice that the OS names are now used as per list, i.e with abbreviations, not expanded as was often the case when they were user-added.

[Teasel]

Meppershall is a good example, as it's about as bad as things get!

So, we have an OLD TRIG, a BOLT, a FLAGSTAFF, a VANE and a CENTRE. With the CENTRE having the exact same coordinates as the OLD TRIG. (What is a centre?!)

So, assuming we're going to split this down into separate loggable trigs per mark, we could have:

Option 1:
1) Meppershall Ch Twr - OLD TRIG, type=OLD TRIG
2) Meppershall Ch Twr - BOLT, type=BOLT
3) Meppershall Ch Twr - FLAGSTAFF, type=FLAGSTAFF
4) Meppershall Ch Twr - VANE, type=VANE
5) Meppershall Ch Twr - CENTRE, type=CENTRE


Option 2:
1) Meppershall Ch Twr - OLD TRIG, CENTRE, type=OLD TRIG
2) Meppershall Ch Twr - BOLT, type=BOLT
3) Meppershall Ch Twr - FLAGSTAFF, type=FLAGSTAFF
4) Meppershall Ch Twr - VANE, type=VANE


Option 3:
1) Meppershall Ch Twr - OLD TRIG, CENTRE, type=OLD TRIG
2) Meppershall Ch Twr - BOLT, type=BOLT
3) Meppershall Ch Twr - FLAGSTAFF, VANE, type=INTERSECTED


I'm leaning towards option 1, as this is the easiest to achieve. I don't like option 3 because it involves throwing away data. (There's nothing to stop a future incarnation of the search engine being able to search for all intersected types, or all pillar, passive or whatever types. So I think we should store FLAGSTAFF distinct from VANE, HOTINE separate from VANESSA etc). But, as for option 1 vs option 2 WHAT IS A CENTRE?! Is it a distinct physical thing, or is it a mathematical construct?

Cheers,
Ian

ps either way, please don't manually create any new trigpoints for the timebeing. The raw OSGB36 data needs to be spread out across the different trigs, and that's better done automatically.

[Teasel]

Also how does the Status field work? (Visible only to admins in edit mode)

If look at your preferences, the "Restrict trigpoint searches to" option maps directly to a range of status values on the admin page. eg "Pillars, FBMs, Curry Stools and similar" will include anything with a status of either "Pillar" or "Major mark".

[agentmancuso]

WHAT IS A CENTRE?! Is it a distinct physical thing, or is it a mathematical construct?

Cheers,
Ian

ps either way, please don't manually create any new trigpoints for the timebeing. The raw OSGB36 data needs to be spread out across the different trigs, and that's better done automatically.

I've always worked on the assumption that a centre is halfway along the highest horizontal edge of the building the OS were looking at at the time; but I don't remember how I arrived at this conclusion, and I have no evidence for it. Not much of a case, I concede.

[peregrinus]

Also how does the Status field work? (Visible only to admins in edit mode)

If look at your preferences, the "Restrict trigpoint searches to" option maps directly to a range of status values on the admin page. eg "Pillars, FBMs, Curry Stools and similar" will include anything with a status of either "Pillar" or "Major mark".

Thanks. ... so it's just a field used to control searches / visibility? Makes sense. I thought it might be some level of OS details I didn't know about