# Guide to Scouting

Discussion in 'Civ4 - Strategy & Tips' started by vicawoo, Mar 7, 2011.

1. ### vicawooChieftain

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Disclaimer: a work in progress. Feel free to contribute.

Scouting is important. Many are people are inefficient. Hence, some algorithms that maximize the scouted area per turn.

Mechanics
A reference which explains later algorithms.

A unit sees all adjacent tiles. Screenshot unnecessary. And thanks for reminding me you can see hills one extra tile away. Sentry units will see them 3 tiles away.

A unit sees two tiles in every direction across water (including lakes), if the line of sight is not blocked. That will be explained in the land example. If a piece of land is across one tile of water, you will see it.

On a hill, you will see two tiles in every direction if not blocked by line of sight. This does not combine with the water line of site, so you will not see 3 water tiles when on top of a hill. You will see 3 with sentry, but I won't talk about that.

This screenshot shows all necessary examples of line of sight. Notice there is a hill 1 east (1E), so we can't see the tile 2 east (2E).
There is another hill 1SE, so we can't see 2SE. You can see it's a forest, but I'm not going to talk about that.
We CAN see the cow 1N2E even though there is a hill 1E, so we can see around. The LINE is not directly blocked, so we can see it.
In contrast, we can't see 1S2E since it is blocked by those two hills. There is no tile halfway in between, so we'd think we could sneak a peak between the two hills, but they form a complete seal to our line of site.
Finally, there is a forest 1N which blocks our vision of the tile 2N (I moved the scout, so we had vision, but it is in the fog). Forests and jungles block just like hills.

So remember: line of sight, forests and jungle and hills block line of sight.

And finally, diagonals are your friend! Assuming you can only see adjacent tiles, moving 1E will reveal the tiles 1N2E, 2E, 1S2E. If you move NE, you will reveal 2N, 2N1E, 2N2E, 1N2E, 2E. 5 tiles > 3 tiles.

Algorithms

The most common inefficient scouting pattern is on the coasts. Here's a dotmap of a corner tile on a coast. Note that cities cannot use the tile 2SW of our helicopter.

Hence there is no point scouting it, at least for scouting city locations.
It is sufficient to scout spot #1 above, which will reveal 1SW, 1S, 1SE, et cetera, 2S1W, 2S, 2S1E, et cetera

along with spot #1 below, which basically covers the eastern tiles.

So if you're scouting the coastline, instead of heading to a corner then moving up, save a turn of scouting by moving to the tile just before, then heading diagonally up.

Due to the map generator's jagged coastlines, this ends up saving a lot of turns.
In the above screenshot, we fully reveal all usable coastal tiles in 5 turns. Whereas if we moved to each corner, it would either take twice as long (10 turns) or we would miss the inner land tiles.

Another example, common in some windy fractal maps.

3 moves is all we need. If we scouted the corners, it would take 5-6 moves.

Sweep arcs and reveal as much as possible

*Under construction

Zigzag scouting
So often backtracking your arc leads you on a fairly straight line. You could just scout a straight line. Or, since moving diagonally takes the same amount of unit moves as moving straight, you get extra scouting by zig zagging 2 tiles back and forth in a direction.

Here's the simplest example: a straight coastline. If we hug the coastline, we only reveal 2 tiles inward from the coastline. Do that for 8 tiles and we've revealed 16 land tiles in 8 turns, along with the sea tiles.

However, if we zig zag 2 tiles in and back, we reveal 3 to 4 tiles in. Note that because of the 2 tile water property, we don't miss any coastal tiles from the first screenshot. A straight line gives us redundant coastal information.

Actually you don't need a coastline, it works with any straight corridor

We can further improve on this by adding a straight line to our zig zags.

Now we always reveal 4 tiles in, which is twice as good as our straight line scout. You cannot do this if you're doing a pure land scout, you will miss the tiles opposite of your line portions If you're curious, mentally check to sea if it grabs all the land and sea tiles.
We can combine the zig zags with the straight lines to gain more scouting. Of course, we can omit some of the straight lines to include more hills for extra vision.
If we do two straight tile moves, we will miss the other side of the zig zag, so be careful.

Of course, you aren't always aware of how far the coastline will remain straight. Moving to 1 in the picture will reveal the water 1N of the deer, and it will also indicate whether the coastline curves in, out, or stays straight to the east of the deer.
You might end up only doing a 1 tile zig zag to anticipate a curving coast (so we can do the corner trick). The zig zag with the straight line will not anticipate the coast curving away, while a pure zig zag will.

You can add zig zags to reveal more territory, but also to get better defensive terrain while not losing any coastal information.

I'll have to include more screenshots on anticipating the coast.

Here we react to the contours. If we saw a straight portion (pretend we started 1S or 1E), a zigzag would be fine if the land moved away (east to west), or lose us at most 1 turn if the land curved inland (south to north).

Under construction.
Remember it will take quite a few turns to sweep out an arc and cover another return arc. If you're too ambitious, you may not end up scouting that peninsula on the other side of your city. So consider scouting it first and start curving around.

You start with a scouting unit, which will cover most major arcs. You will often build another unit before you build a settler, and sometimes it will have time to cover smaller arcs in the opposite direction.

Tips
-Coastal resources aren't as valuable early since you have to build workboats for them, so for your first arc around your city, feel free to ignore them. Your next few arcs, scout along them to find neighbors and establish the limits of your arcs.

-Animals spawn at turn 5. They won't spawn within two tiles of your scouting unit, so you have a few more turns. After that, scouts especially are vulnerable on open ground since they effectively get a lower difficulty bonus to animals. So be extra aggressive on scouting those open areas those safe turns, so you can scout safer, forested/hilled areas later.

-Once you've scouted city locations, you can scout those corners to check for islands. Check the tile yields to see if what you expect to be ocean tiles are coastal tiles.

-Your city gets site of every tile within your culture. So remember your first border pop get 2 tile vision from hills in your outer borders, meaning you can scout around it and reveal more tiles instead.

-Your second border pop won't be in time for your second city, and the tiles they reveal could be important. However, as long as huts aren't on, a non-tundra forested tile on most maps will not have a special tile except a calendar resource, which you can't improve. You will be able to see the edges of that tile, so you can scout around it.

In the screenshot below, we see there's a forest 4NE. It might contain a calendar resource, but since we see it at turn 50, we can arc around it.

-Huts, you should probably alter your philosophy to maximize tile vision at the cost of thoroughly scouting your adjacent lands. Hills are your friend, jungle not so much.

-Jungle areas tend to be thick and unusable early, so save it for your second or third scout.

2. ### TheMeInTeamTop Logic

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Actually there's a lot of point, because seeing that tile have a yield suggests it's within 2 tiles of SOMEWHERE, and settling a city in that corner has a good chance of creating a culture bridge pre-astro. More importantly, this can often lead to additional land/moar civs.

Coast scouts are less efficient, but also less likely to die a horrible death to barbarians and more likely to identify land chokes/peninsula/continent shape, making efficiency vs importance of information obtained a real tradeoff.

3. ### vicawooChieftain

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That's included in the tips in checking for islands. But you're not going to make your second or third city for that purpose.

4. ### Nick CarpathiaUnleash the HAARP

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Here's a nice summary of the visibility rules.

http://realmsbeyond.net/forums/showpost.php?p=50117&postcount=827

The gist is, your baseline units either see 1 tile if standing on flatland, or 2 tiles on hills. If you're on a hill, your vision is absorbed by rough terrain. If there is a hill just outside this 1-2 tile vision radius, it will get defogged anyway.

Peaks are a special case, because units can't physically stand on them. However, if they're inside your cultural borders, then it acts as if a unit with a vision range of 2, with the corollary that its vision doesn't get absorbed by hills or forests, but will by forested hills.

5. ### NihilZeroWHEOOHRNY

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While seeing as many tiles as possible as fast as possible is nice, it may be that the most efficient approach is the one that keeps your scout alive longer, allowing you to scout a higher total number of tiles by the time you can actually do something with your knowledge. Losing your first unit can be a pain because sometimes it will be a long time before you get another one, meaning that you get bugger-all scouting done.

Unfortunately, given the vagaries of animal and barb peregrinations, it's rather difficult to make a foolproof plan for survival. Sometimes you just get eaten by bears and that's all there is to it.

If you have a scout as opposed to a warrior, you might consider moving only one tile in open ground and saving a movement point to beat a hasty retreat. I never do that, too impatient.

Then of course there is the tradeoff of scouting versus spawnbusting. Just say you are lucky enough to have your starting unit cover some ground and reveal some map. When is it time to skirt back closer to the capital and take up spawnbusting duty? The same goes for subsequent warriors. While it's tempting to send them off to search for juicy city locations, often it is necessary to keep them nearby for defence and spawnbusting.

6. ### babarKing

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Thanks for the tip about the coastal corner. This never occurred to me (how long have I been playing this game...?). However I agree with TMIT about the coastal scouting, and in addition, the presence of seafood can completely change your dotmap.

7. ### TheMeInTeamTop Logic

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While it won't matter for your 2nd city, it can certainly matter if you're planning for iso vs not (tech wise) for example, or when considering GLH (which on high levels is something you get between city 1-3 if you really want it).

This is a good guide; I'm just pointing out that some things that are strictly inefficient can be reasonable for other reasons. A coast hugger is what...roughly 3/8 less likely to get insta-gibbed by bear cavalry/whatever?

On the flip side, seeing the land in the immediate vicinity of the capitol where you're actually going to settle can *also* influence tech choices, although often the spawnbust warriors get sufficient scout info in time (standard worker ---> warrior).

8. ### vicawooChieftain

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I forgot to include the seeing the hills an extra tile away, good to point that out.

I need more screenshots to explain the coastal savings better and the other two rubrics.

9. ### vicawooChieftain

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Explaining arcs and when to start/begin them is going to be tricky, I don't know how long that will take to compose. It's the most theoretical part. Whereas the coastal corners and zigzags are in practice very straightforward.

10. ### babarKing

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Nice guide vicawoo. I was wondering about those zigzag scouts with the green circles - is there a way to set them on their path and forget about them? I often don't scout that efficiently out of sheer laziness.

11. ### vicawooChieftain

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You can waypoint tasks if you hold the shift key, but I wouldn't recommend it. I wouldn't even recommend moving a scout two moves without checking the first move, you'll get your unit killed too often.

Once you've absorbed these methods, scouting becomes pretty fast and automatic. There's not a lot of thinking involved, just see the terrain and react.

12. ### babarKing

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Hmmm. Doesn't work because of my mac mouse anyway. Yeah, I wouldn't do that with scouts (I was thinking more of scouting warriors), since it would waste many 2nd moves as well as being dangerous.

13. ### lites10Chieftain

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I have no problem doing it with my mac mouse, had to try it just to check. do you not have your mouse set to have left and right buttons like a normal mouse?

14. ### vranasmDeity

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nice guide, some interesting insight on the whole problem.

I don't agree with 1 screenshot partly though. That's the one where you have warrior going straight NE in 5 parts. for the first 4 it is OK.
But the step from 4 to 5 should be imo on the PH to the east and not to lake.
It's true you don't miss on coast tiles, but there is workable ocean tile you miss to see and ocean tiles usually hold fishes and the way this map turns I would say with the long coast without any seafood would tell me there has to be fish.
Fish in ocean is good tile since it can't be pillaged by some lame galley, but costs workboat. But I definitely plan my cities around fish tiles (actually yesterday in my latest LP I made the classical error with not scouting deep enough on coast and totally missed fish and killed 1 city spot that could be probably better placed)

15. ### vicawooChieftain

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That is correct, you'll miss the ocean tile 2SE of that plains hill. Good eye!

The terrain in these screenshots are mostly randomly generated because it's too much effort to worldbuilder lots of terrain, and I was pretty lucky to generate such a long diagonal coastline, so I just went with it.

On the coastline debate:
Though I feel I have a good algorithm for scouting coastlines, I tend not to scout it until I've revealed the land tiles about 2 arcs (8ish tiles) away, although that's certainly not a strict rule.

If you want to scout the coastline to avoid barbarians, wouldn't you want to reveal the land tiles before they get especially dangerous (archers and such)? Hence it's still better to reveal the land around your capital as fast as possible, then switch to coastlines. It'll also prevent a few more spawns.
You only start with one warrior/scout, and it's very costly to replace earlier, which means you want the most scouting you can get out of it. Whereas later on, you can produce multiple ones while growing and you can build enough to compensate for the "less efficient" coastal scouting and discovering coastal trade routes.

16. ### babarKing

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I think so, I use the right click all the time. Couldn't do the liberalism trick either, but both work if I plug in a pc type mouse (just checked). No big deal, although it would be nice to be able to queue up worker actions that include moving.

17. ### Riflin'JoePrince

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I find this quite over-theoretical. For the most part I prefer to scout as safely as possible, rather than risk ending a turn necessarily on open ground for the sake of speed. Losing that initial unit is usually a serious setback (although its still common enough to blunder straight into a bear anyway). Information about the surroundings is more important than so-called goody huts.

18. ### Nick CarpathiaUnleash the HAARP

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I'm being pedantic here, but the word you're after is heuristic. It's a fancy way of saying "guideline", in a situation resembling X, you do Y.

@Babar, what is this "Liberalism trick"?

19. ### babarKing

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I should have said "cheat". I can't remember exactly, something to do with left and right clicking at same time on the free technology. You get the tech, and then the choice of another free tech, and you can repeat the process until the whole tech tree is finished. Great fun! Not really, it's completely lame obviously. I'm not sure if it works in the latest patch.

20. ### vicawooChieftain

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Is this worth finishing? I'd rather not invest time if there's little benefit.