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What does the "vicinity" of an alien base mean?


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#1 erasmus_b_dragon

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Posted 31 January 2012 - 04:08 AM

"To locate one, an X-COM craft must patrol in its vicinity for a short time" OK, suppose I want to search for an alien base in Europe. Is the "vicinity" of a base 200 miles? 500? 1000?

To make sure I find it if it's there, would I have to patrol in (note: some of these are not shown on the xcom map):

Spain, France, Germany, Poland, Belarus, UK, Italy, Greece?

Or only UK, France, Germany, and Greece?

Do all xcom craft have the same detection range?

Next time I guess I will save the game and, after I find the base, reload and try different patrol locations to see what the max detection range is.
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#2 noonesshowmonkey

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Posted 31 January 2012 - 10:48 AM

"To locate one, an X-COM craft must patrol in its vicinity for a short time" OK, suppose I want to search for an alien base in Europe. Is the "vicinity" of a base 200 miles? 500? 1000?

To make sure I find it if it's there, would I have to patrol in (note: some of these are not shown on the xcom map):

Spain, France, Germany, Poland, Belarus, UK, Italy, Greece?

Or only UK, France, Germany, and Greece?

Do all xcom craft have the same detection range?

Next time I guess I will save the game and, after I find the base, reload and try different patrol locations to see what the max detection range is.


http://ufopaedia.org...e=UFO_Detection

The effective range is 600 miles, or approximately 1 inch diameter around the aircraft on the Geoscape.

However, aircraft must patrol within 1500 nautical miles of the base to locate it, meaning their detection range is more than doubled their radar range.

Edited by noonesshowmonkey, 31 January 2012 - 11:09 AM.


#3 erasmus_b_dragon

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Posted 31 January 2012 - 06:17 PM

http://ufopaedia.org...e=UFO_Detection


Thanks. I had searched using other keywords (alien base detection) and didn't find it.

The effective range is 600 miles, or approximately 1 inch diameter around the aircraft on the Geoscape.


Wouldn't the distance on the map depend on the screen size, resolution, and zoom in/zoom out?

However, aircraft must patrol within 1500 nautical miles of the base to locate it, meaning their detection range is more than doubled their radar range.


That is the key fact. I can calculate map distances from that. Assuming that the wiki writers didn't write "radius" when they meant "diameter," and the makers of the xcom made the distances something like real world distances, 2 patrols will cover the total surface of Africa. The distance between Cairo and Capetown is 7200 km, and the diameter of a search is about 5500 km. Also one patrol in Berlin will cover all of Europe and part of Africa.
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#4 yarrow

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Posted 31 January 2012 - 10:09 PM

'vicinity' means nearby, right? :D :D :D :D :D
seriously, don't dig too deep, no magic here

basically, there are only 3 rules to remember

first of all:
your craft MUST be on PATROL mode!!!
NOT enroute, NOT chasing after landed ufo

secondly:
target correct area
( this is the hardest part )

thirdly:
the longer the distance from alien base to your patrolling craft
then longer 'patroller' MUST search the area
( patrolling even for whole day in extreme cases )

following ufopaedia entry:
http://ufopaedia.org...g_an_Alien_Base
is slightly misleading here, the following statement
'X-COM craft must patrol in its vicinity for a short time'
should be read as 'at least for a short time'


that's it!
if you target correct area AND patrol it for long enough
you will find aliens no matter what
( they don't possess cloacking devices :D )



simplest method to find correct area is to ...
just wait for supply ship to show up, as it lands on top of alien base!
so, it shows you the EXACT location to patrol
( aliens are kind of stupid ^_^ )
http://ufopaedia.org...nal_Information

or ...
if you see alien ship(s) landed ( when alien base is being first constructed )
you can just send your interceptor to ufo landing site
or set waypoint just in between landed alien ships
( with a bit of practice you will find their base very easily )
http://ufopaedia.org...itle=Alien_Base


or ...
if you see country withdraw funds, just search that country region
( there is alien base out there somewhere )
http://ufopaedia.org...en_Infiltration


or ...
if you don't see alien ships, still don't search blindly, but check graphs instead
sometimes just simple look at them may show you the destination region/country
or at last narrow area(s) to be searched

and finally
good 'sweeping' method is what I call a 'chess-board' style search :)
patrol systematically each square spaced by distance approximately
the same as is from northern to southern UK
( it is slightly too 'dense', but it works quite well )

happy patrolling :D
yarrow

Edited by yarrow, 02 February 2012 - 05:36 PM.


#5 erasmus_b_dragon

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Posted 01 February 2012 - 08:00 AM

and finally
good 'sweeping' method is what I call a 'chess-board' style search :)
patrol systematically each square spaced by distance approximately
the same as is from northern to southern UK
( it is slightly too 'dense', but it works quite well )


Actually, according to the wiki, that is far beyond "slightly" too dense. Your plan is based on the search diameter being about 600 km, while the wiki says it is about 5500 km!
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#6 yarrow

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Posted 01 February 2012 - 09:25 AM

of course you are right about the numbers, but ...
numbers are not the only thing to consider

please note that in practice those areas you search
must overlap slightly, just to make sure you didn't miss anything
http://www2.stetson....edma/circovsqu/

in my experience you can assume 80% of the size
of the yellow circle shown below
http://ufopaedia.org...etection_Ranges

it's approximation is good enough, if you want to be on the 'safe bet'

yarrow

Edited by yarrow, 01 February 2012 - 09:34 AM.


#7 erasmus_b_dragon

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Posted 01 February 2012 - 03:51 PM

please note that in practice those areas you search
must overlap slightly, just to make sure you didn't miss anything
http://www2.stetson....edma/circovsqu/


You are absolutely right.

in my experience you can assume 80% of the size
of the yellow circle shown below
http://ufopaedia.org...etection_Ranges


It's possible that the wiki gets the radius and diameter of a patrol mixed up. Is it a strange coincidence that the diameter of a craft's radar for detecting alien UFOs is 1500 NM, and the radius of a patrol area is also 1500 NM (according to the wiki)?

I read the discussion page of the UFO Detection page http://ufopaedia.org...etection_Ranges, and the comments suggest that some of the values for radar in the xcom game files are theoretical, and actual in-game distances are smaller.

What we need is a new wiki page for alien base detection. As I suggested in my first post, I need to use a saved game just before a patrol detects an alien base, reload that game several times, and try a new patrol distance each time, to get the max distance. (I probably would need help creating the wiki page though.) This would assume that the game does not randomize the base location before it is detected. That would make such an experiment impossible.

What I want is an alien base search method you can use in the game before you have a hyperwave decoder. Of course, if you can see where all the alien base missions are going, you patrol there.
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#8 NKF

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Posted 02 February 2012 - 12:12 AM

Searching should be no less easier or harder with the hyperwave decoder, since only active searches or the mysterious X-Com 'agents' can locate alien bases. So any search method you come up with will be useful throughout the game.

edit: dah - I've just gone and duplicated what's already said in the articles. Snipped for brevity.


As for the wiki, if you can edit plain text, then you are ready to make wiki articles. Just remember that to make new pages, you need to first create a wiki link to it from an existing article. You can easily learn the basics like how to make wikilinks by looking at the source code for the pages when you edit them. There are some editing standards to apply - but people like myself and other (semi) regulars can sort that out. ;)

Also, after re-reading the article, judging from the context used, the numbers thrown at you are the radius from the radar. The graphic overlay showing the numbers in the mid section are clearly diameters.

Perhaps it would be clearer if the whole article were re-written to just use radii?

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Edited by NKF, 02 February 2012 - 01:02 AM.

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#9 yarrow

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Posted 02 February 2012 - 09:12 PM

I guess I didn't put it clearly enough ^_^

the only hard part is ... to find CORRECT PLACE to patrol
craft detection distance ( whatever it really is :D ), can only make it easier or harder

before HW decoder era, you can take advantage of 2 simple facts:
1.) with radars you CAN distinguish ( explicitly by picture ), if it is supply or terror ship ( or battleship ... etc )
2.) you can't get 'alien ship landed' wypoint from terror ships ( only crashes, not green waypoints )

so, when you see large ship landed ( green waypoint )
you can safely assume that it is supply ship on one of those missions:

a.) base construction ( good region to start 'chess-board' patrols arround )
http://ufopaedia.org...itle=Alien_Base
http://ufopaedia.org...en_Infiltration

b.) supply mission itself ( exact place to patrol )
http://ufopaedia.org...le=Alien_Supply

veterans also use the other methods which can help:
- fleet composition ( sizes and quantities )
- current speed ( and if it changes )
- flight paths prediction ( where they go )
- graphs prediction ( activity regions )

if you master them, aliens won't be able to hide from you :D


as for the article
http://ufopaedia.org...etection_Ranges
it says:
'Detection range of a Small Radar/Sonar (3000nm diameter), also maximum "base detection" range for craft'
so, it is only the max distance at which craft is able to detect
that is why I will suggest ( again and again if nessesary ^_^ )
that you should narrow your area to the yellow circle, as I written earlier


to make some kind of proof of my gameplay observation
I did a quick alien base detection 'efficiency' test

I tested 1 + 10 times to detect alien base for both circles ( yellow and green )
and first test was used just to know where the base is exactly located
( I was lazy as hell_ll :) and just waited for supply ship to show up, which took only few days LOL )

waypoints were set not excessively precisely
just more or less where the circles show their max distances

within larger/green circle ( max base detection range )
interceptor did NOT find the alien base 3 times!!! OMG
the 'out of fuel, returning to base' message appeared after ~1.5 day of patrolling
( I blame my poor accuracy )

within smaller/yellow circle ( craft detection range )
alien base was always found, within 2-3 hours max ( much faster )

to me conclusion is very simple:
with my 'waypoint accuracy' ... I will stick with the yellow circle ^_^


finally
as :D medium tank :D said:
patrolling is independant from any radars/HW decoders your bases have
HW decoder 'only' gives you additional info about detected UFOs
with this info you should be able to get even better clue where to search


yarrow

Edited by yarrow, 02 February 2012 - 09:19 PM.


#10 erasmus_b_dragon

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Posted 03 February 2012 - 01:07 AM

Searching should be no less easier or harder with the hyperwave decoder, since only active searches or the mysterious X-Com 'agents' can locate alien bases. So any search method you come up with will be useful throughout the game.


That's not what I meant. I meant to say that the entire task of deciding if, when, and where to patrol becomes easier with the HW decoder, and that in exhaustive searches (which I resort to before I have the decoder), it's quite possible to forget exactly where you have and have not searched. Part of the problem with large radar is that it is not as reliable as the decoder. The wiki also says that the closer your patrol craft, the faster it will find the base, and of course the decoder helps you get closer.

Therefore, before I have a decoder, I think it really helps to know what the search radius is. The information was there in the wiki, but I didn't expect to find it in the
UFO detection" section. AFter the other poster gave me the link, I noticed that the wiki correctly states that the green circle is for both small radar and base detection.

As for the wiki, if you can edit plain text, then you are ready to make wiki articles. Just remember that to make new pages, you need to first create a wiki link to it from an existing article. You can easily learn the basics like how to make wikilinks by looking at the source code for the pages when you edit them. There are some editing standards to apply - but people like myself and other (semi) regulars can sort that out. ;)


Thanks. I want to think about what I want to say before I start editing, of course.

I saved a game before detecting a base, but the experiment I had in mind (patrolling at various distances from the base) did not work. because the game sticks the base at different locations, even if you play from the same save. The first time I detected the base, it was at the north pole. I tried to detect it by patrolling at the north end of Scotland, which is farther away from the pole than 2775 KM, and sure enough, my patrol did not find a base. .

Then I tried patrolling at the same place, but in that case, the game stuck a completely different base on the map, closer than 2275 KM, and the patrol did detect it. At least the radius of 1500 NM seems correct.

Also, after re-reading the article, judging from the context used, the numbers thrown at you are the radius from the radar. The graphic overlay showing the numbers in the mid section are clearly diameters.

Perhaps it would be clearer if the whole article were re-written to just use radii?


I'm not sure I want to expunge completely the word "diameter." The diameter helps you think how many circles it takes to cover an area completely. It would be nice if the game drew a patrol circle for you, but....
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#11 NKF

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Posted 03 February 2012 - 01:56 AM

It's possible your test save was made just before the location of the base was officially decided? An established alien base should theoretically stay in the same location.

If you don't mind hex editing and experimenting a bit, you can 'hide' an existing alien base so that you can go out and relocate it. You can refer to the following for the gory details:

http://www.ufopaedia...p?title=LOC.DAT

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#12 erasmus_b_dragon

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Posted 03 February 2012 - 04:30 PM

It's possible your test save was made just before the location of the base was officially decided? An established alien base should theoretically stay in the same location.


I don't know what's going on in this save, made before I detected the first base (also before the HW decoder detected several alien base missions in the arctic). Is it a coincidence that my first HW decoder was just finished? It's almost as if the game wants to go out of its way to place the base in range of where I decide to patrol, most of the times I try it.

Maybe the game decides the base location after those ships (scout, supply, battleship) on "alien base" missions finish doing some recon and other preparations. I'll try patrolling after those ships have landed.

If you don't mind hex editing and experimenting a bit, you can 'hide' an existing alien base so that you can go out and relocate it. You can refer to the following for the gory details:

http://www.ufopaedia...p?title=LOC.DAT

- NKF


Thanks, that might do the trick.


I tried to do a patrol from the same place (the top of Scotland, out of range of the north pole) several times, after loading the save with no bases detected, and from that patrol location, (or very close -- I can't make it exactly the same with my mouse), out of range of the north pole, I detected Base 1 in 2 different locations, but one time it detected nothing. I also patrolled in range of the north pole, and it detected Base 1 at the north pole, but I am not sure that always happens.
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