Hi xxiii,
Lots of questions! I'll try to answer them the best I can.
While eddiscovery can't seem to be able to submit right now, is it safe to submit via the website? It seems to be working, I just want to make sure the data won't be lost that I'm submitting right now.
We had an issue over the week-end but as long as the frontedn is working and your are using it, no problem all things are saved!
Should my web and eddiscovery submissions eventually merge, or do I have to explicitly request it (in which case... my cmdr name: Backer #469732, and do future entries stay merged?)
We can merge old guest accounts with your EDSM account, I have done it for you already. As long as your CMDR name stays the same, we should be able to merge them.
What format are the distances stored in? (single precision, double, decimal/numeric) and what format are the calculations done in? (I'd also like to ask this question of Frontier).
All our distances are stored as INT, we multiply the submitted one by 100 so calculus are easier and faster.
Is there an API to get all systems (and/or distances) submitted by a particular CMDR? (perhaps along with the ability to restrict to only systems with insufficient distances, or other criteria)? (I was trying to find all the systems that I've done, but had to do a date-restricted query and then search for my name).
Not for now, but that can be something we add on our TODOLIST.
asks for "we need more distances": Is it picking some additional systems (ones with only a few distances?), and then calculating what it thinks the distances to those systems should be and asking me to confirm (or dispute)? When additional systems are added to a system, does that allow its position to be more precisely determined? (It seems with enough relationships it should be possible to more precisely determine (beyond 1/100 of an LY that ED shows in the galaxy map) where a system is; is it doing this? Hm, I guess so ("It is located at -103.375 / -138.3125 / -339.8125"), but this ties into my next questions.
Positions are not more precise. We start calculating with 5 distances, it works or not
The suspicious tabs works only when we have the coordinates, it is mainly used to help us see what distances are wrong by checking them in game.
How many distances does a system need before its considered correct?
Systems are considered correct as soon as their coordinates are calculated. We may ask more distances to verify when we have less than 8 distances.
That is mainly to help us when we double checks the coordinates, we need a little more to process bad distances. But it does not change the coordinates.
Are distances bidirectional (If I say Maia is X from Polaris, I'm also saying Polaris is X from Maia). Do both systems get adjusted if necessary (and what then happens to systems that have distances to those?, when a system "moves" how is this propagated throughout the database?) I presume (for efficiency/speed reasons) that systems are stored with their coordinates, and not just as distances from other systems, but then these coordinates have to be updated when necessary.
Yes they are bidirectional. We only store them once, with the system with lower ID as ref_system1. But they are used for both system. Once calculated, coordinates are stored so we don't have to check each time.
If the lists contains systems with no coordinates we try to calculate them on the fly.
We have internal tools that check all systems to compare every coordinates with the stored ones so it helps us catching bad coordinates/distances sometimes, but so far all coordinates are correct.
We may have some coordinates we cannot recalculate because some bad distances where submitted after the first calculation.
Some we cannot calculate because they come from EDSC, most of the time, we cannot calculate them because we found alternative possibilities.
On all the database, they are only 360 of these cases over 38000 calculated coordinates, so it does not happen much ^^
Asks for "We need more distances to calculate coordinates", Its picking systems with too few distances currently, and asking me to add a distance from where I am to it (and it to where I am)?
Yes from where you are.
I can only "hide distance" for values I've provided; and this means it will no longer consider that distance when doing calculations?
As we import data from other third party tools, sometimes bad distances came back in the system!
Hiding them prevent that behavior, if we delete them, they would come back eventually over time. They are not used in calculation.
Also, curious what method(s) are being used to calculate the coordinates of systems, and how are minor discrepancies resolved (such as might arise if using binary floating formats).
As pointed out by
RedWizzard, we use
Trilateration. We should put something to explains better exactly how we handle cases ^^
On at least two submissions now, Polaris is 1/100 of an LY off (according to eddiscovery), but I submitted it anyway with the value that the galaxy map told me (perhaps polaris is right in the middle of where the galaxy map says it was, and where it was calculated to be (at least by eddiscovery))? One of the systems with the discrepancy is Wredguia WK-X b28-0. Unfortunately, I didn't note the other one, but when Polaris was "off" for a second time, I started to get suspicious.
As you can see here (
Polaris) we have no rounding problems on Polaris distances.
You can have a better look on how we calculate the coordinates here:
http://www.edsm.net/system/check-coordinates/id/25526
1/100 Ly off can happen but not much, we have try to handle them but results over the whole database where not good so we do not handle them for now ^^
They are shown in orange on distances listing.
The only thing we do for now, is that if we have more distances we can remove one distance from the calculation if we think it's wrong. Sometimes it helps the systems to find the coordinates.
