I have created a line of sight calculator and posted it to GitHub. I've started out with the current tournament maps but definitely plan to add campaign maps and skirmish maps outside current rotation.

https://nick-hansen.github.io/ia-los/

To use the tool, select a map, place your attacker (blaster), place a defender (target), and possibly some blocking models (shield). The map will default to the first line of sight it can display, or none if line of sight is not possible. If more than one line of sight is available, you can change the Lines of Sight dropdown to view them.

The lines drawn on the map are not pixel perfect. The grid is there to help players select spaces, and view results. The actual calculations are performed in code, not the displayed image.

I hope this project helps Imperial Assault players, speeds up situations where its tough to tell how close a shot is, and enhances the game.

I want to thank Nick (nickv2002) for granting permission to use the map images from the Imperial-Assault-Skirmish-Map-Project GitHub project.

Added Features

• Attacker View - highlight all tiles to which Attacker has line of sight
• Defender View - highlight all tiles which have line of sight to Defender
• Comprehensive View - which tiles can this tile see? Which tiles can see this tile? Which tiles have mutual line of sight?
• Clear button to remove Attacker, Defender, and all Blocking models
• Rules have been updated to prevent shooting around edges
• Rules have been updated for which edges block LOS
  • fixed bug caused by this update
• Rotating the map
• Added Tutorial map to Core Campaign after player request
• All Skirmish maps added

Current Requests:

• Displaying deployment zones
• Displaying/Removing doors
• Displaying Exterior/Interior areas
• Odds for making range from square with a given dice pool
• Add Campaign Maps for other campaigns

Please report any bugs found with maps, and requests for enhancements in this thread! 🙂

Looks good. I tried out a few potentially tricky situations, seemed to get them all right. ? Nice work.

Obvious enhancement requests:

• If the attacker is in "this" square, what are all the target squares that he can see?
  • If he's got "this" dice pool, what's the chances of him hitting a target in those squares at that range?
• If the defender is in "this" square, what are all the attacking squares he can be seen from?

The idea being people can plan positions with the best fields of fire and safest from being shot at - more than just specific attack situations.

13 hours ago, Bitterman said:

Looks good. I tried out a few potentially tricky situations, seemed to get them all right. ? Nice work.

Obvious enhancement requests:

• If the attacker is in "this" square, what are all the target squares that he can see?
  • If he's got "this" dice pool, what's the chances of him hitting a target in those squares at that range?
• If the defender is in "this" square, what are all the attacking squares he can be seen from?

The idea being people can plan positions with the best fields of fire and safest from being shot at - more than just specific attack situations.

Thanks for the feedback Bitterman. I'm going to start tracking requests in the first post, so that people can see progress ?

Wow. This tool is super! Instant bookmark!

59 minutes ago, Sarge144 said:

Thanks for the feedback Bitterman. I'm going to start tracking requests in the first post, so that people can see progress ?

I look forward to it. It'd also be useful to combine my two previous suggestions, and show them both together, at the same time. So, if I'm at position XY, what other squares have got mutual LOS, what can I see that can't see back, and what can see me that I can't see... if you see what I mean.

Very nice job.

Thanks.

This case is an bug or not ? :

Not a bug as far as I can see. Just a fun consequence of how line of sight works.

(Neither line goes into/through a wall, door, blocking terrain, or figures , or energy shield .)

46 minutes ago, EnderWilfrid said:

Very nice job.

Thanks.

This case is an bug or not ? :

a1bert is correct, although this is a REALLY interesting case. The top line goes -4, -1 twice. The first time, glancing the corner of an off map tile, the second time, the corner of a blocking edge. The bottom line doesnt contact anything at all. No lines of sight are blocked.

Selecting grid view can help with some of the visual discrepancies as well.

1 hour ago, Bitterman said:

I look forward to it. It'd also be useful to combine my two previous suggestions, and show them both together, at the same time. So, if I'm at position XY, what other squares have got mutual LOS, what can I see that can't see back, and what can see me that I can't see... if you see what I mean.

I think I see what you're saying - sort of which tiles can i see, which tiles can see me, and which tiles have mutual line of sight. That's a cool idea. I'll think about this one a bit. Should it be a separate option from the others? I know it would be helpful when planning attacks to know if someone has line of sight back (Han, Greedo).

1 hour ago, aermet69 said:

Wow. This tool is super! Instant bookmark!

Thanks! Hope the tool is helpful!

This is great! Good work!

1 hour ago, EnderWilfrid said:

Very nice job.

Thanks.

This case is an bug or not ? :

Hah! That's pretty funny, but no, it's not a bug.

58 minutes ago, ManateeX said:

Hah! That's pretty funny, but no, it's not a bug.

That might be one of the funkier LOS technicalities I've seen.

2 hours ago, Sarge144 said:

I think I see what you're saying - sort of which tiles can i see, which tiles can see me, and which tiles have mutual line of sight. That's a cool idea. I'll think about this one a bit. Should it be a separate option from the others? I know it would be helpful when planning attacks to know if someone has line of sight back (Han, Greedo).

In my head, I'm thinking: checkbox for "what can I see", checkbox for "what can see me". If neither, or only one, are selected, it's easy. If both are selected, then maybe: highlight green for I-can-see-them-but-they-can't-see-me, blue for mutual LOS, and red for they-can-see-me-but-I-can't-see-them. Something like that?

3 hours ago, a1bert said:

Not a bug as far as I can see. Just a fun consequence of how line of sight works.

Wow - I don't think I've ever previously seen a case where there's something between the two lines, but you still get LOS. That's amazing.

IA's LOS rules are really interesting. They're probably the most satisfying grid-based LOS solution I've ever come across, once you get the hang of it (most games go for "can you draw a straight line from the centre of one square to the centre of the other", which is simpler, but horrible to actually use); but they can be quite a pain for people to grasp. The hero players in my group still don't get it after seven full campaigns and end up just asking "can I see that guy from where I am?", and probably about half the skirmish players I come up against are the same. No amount of explanation or pointing them at the appendices seems to get through.

While I think firing positions at corners is a really interesting mechanic, situations where you shoot back around the corner, like this...

...are so counter-intuitive that people seem to panic and give up on making any sense out of it. Which is a real shame, but I can understand their viewpoint too.

Bitterman, that's exactly what I thought - the los solution makes sense, but It can be unintuitive or difficult to eye-ball especially over long distances.

Being new to the game, LoS was difficult to pick up, and I figured I cant be the only one having trouble. I figured a program could calculate this WAY faster and show it's work ?

Very interesting, but I'd certainly rule against it in my house campaigns. Rules are one thing, but just because no one thought to specify that stuff mustn't block the field between the two sighted corners, I'd go with common sense here and say, 'nope, you can't shoot that dude'. This is an extreme case to be sure, but still...

So you'd say you can't shoot this guy? Because that's effectively what this situation is.

Do what you like in your games of course (if you can convince your fellow players anyway), but players will make unfairly bad decisions if the rules change arbitrarily.

8 minutes ago, angelman2 said:

Rules are one thing, but just because no one thought to specify that stuff mustn't block the field between the two sighted corners, I'd go with common sense here and say, 'nope, you can't shoot that dude'. This is an extreme case to be sure, but still...

I don't think this is at all an extreme case. The attacker can see most of the target in this case. You have much less of a "figure's face" visible in line of sight situations on average.

I would have a much weirder special case that would be theoretically possible and be totally unthematic, but it is possible to avoid by thoughtful map generation (and with a little forward thinking when creating tiles).

Besides, you can totally draw "regular" line of sight to the target's bottom corners without leaving the blocking edge in their middle.

11 hours ago, angelman2 said:

Very interesting, but I'd certainly rule against it in my house campaigns. Rules are one thing, but just because no one thought to specify that stuff mustn't block the field between the two sighted corners, I'd go with common sense here and say, 'nope, you can't shoot that dude'. This is an extreme case to be sure, but still...

But IT INDEED IS specified, that "printing errors" like this do not block LoS.

17 minutes ago, DerBaer said:

But IT INDEED IS specified, that "printing errors" like this do not block LoS.

Except we're not talking about the wall graphics extending outside of the corners here. Blocking terrain covering a full edge is not graphical detail, it is blocking terrain placed between spaces and the effect of the terrain affects that edge.

However, like I said, you can draw line of sight without leaving the blocking terrain between the lines, and there's not even a thematic reason to make exceptions to the LoS rules.

1 hour ago, a1bert said:

Except we're not talking about the wall graphics extending outside of the corners here. Blocking terrain covering a full edge is not graphical detail, it is blocking terrain placed between spaces and the effect of the terrain affects that edge.

Usually, I do rather not disagree with you, but in this case you are wrong.

1 hour ago, a1bert said:

However, like I said, you can draw line of sight without leaving the blocking terrain between the lines, and there's not even a thematic reason to make exceptions to the LoS rules.

But you are absolutely right here, so there is no reason to argue ...

I'm not saying that you couldn't draw line of sight to that corner (I already indirectly said the app drew valid line of sight), just that the blocking edge is not such a detail to ignore. (The blocking edges being in between the LoS lines were the reason for angelman2's objection. The other way to draw line of sight avoids the objection.)

4 hours ago, a1bert said:

I'm not saying that you couldn't draw line of sight to that corner

Then this was just a misunderstanding. Sorry.

On 9/15/2018 at 12:41 AM, a1bert said:

Besides, you can totally draw "regular" line of sight to the target's bottom corners without leaving the blocking edge in their middle.

This, for me, changes the argument and I would now accept it in my game. It was the 'blocking item in the middle of your cone of fire' that I didn't like; this however, is clearly fine.