Determining radius with squares

[dcollins]

Gee, it's great to know some folks are finding my website of use. (Pre-internet, this stuff would just sit on my hard drive for only me to look at

dcollins' templates are great, but how come he doesn't list a 15-foot radius centered on a square? I think he needs to add that one.

I believe when I surveyed the core rules, I didn't actually find any spells that could be cast on a person/object target with a 15 ft. radius effect. Similarly, there was exactly one spell with a 25 ft. radius spread, so I skipped that one, too, in the interest of brevity.

The method I have always used is 'counting squares' - basically, I count the distance in squares from the center square to the potential target, using the 5/10 rule, and use that figure to determine whether or not it is affected.

Anyway, for that method, using the 10' radial area centered on a square, I get this result... which is significantly larger (8 squares) than yours...

That's correct. You'll notice in the explanation just before the "centered radial" templates I note this: "These square-centered templates are designed to duplicate the number of spaces covered by the line-intersection versions..."

Using the normal 5/10 count rule on a square-centered effect gives a whole bunch more squares in the area than when centered on a crosshair. Since the DMG only officially mentions crosshair-centered spells, I decided to give those areas priority, and scale back the square-centered versions so the don't suddenly grab a lot more area. (Even so, they're +1 space larger.)

That's why you see the discrepancy -- the alternative is to have areas blossom much larger when centered on a square instead of a crosshair.

 

[kreynolds]

I partially agree with drnuncheon, only on the grounds that it makes no sense to target the area next to a target character, or creature,(ie: the corner, or intersecting grid lines).

Page 69 of the DMG states that you might need to make some adhoc rulings in regards to area spells (meaning you will need to draw the area and determine which squares are effected, but it in no way states that you should not use an intersection of lines). It also states that burst areas, emanation areas, and cone areas need to have an intersection of lines designated for the point of origin. Granted, these are to be used as guidelines, but you'll note that all of the illustrations for area of effects on pages 68 and 69 use an intersection of lines. It then states, under Miscellaneous:, to apply the aforementioned rules as best you can to other areas.

This aids in the quick placement of spells, as well as an accurate representation of the affected area. If you don't use an intersection of lines, your effected area will be bigger, thus innacurate.

To put it simply, the DMG states that you pick you intersection of lines and draw the area of effect in the simplest form. If the area covers the majority of a square, the square is fully affected. Figuring up a fireball is easy. Figuring up a cone launched at the diagonal can be a bit of a pain, but its still quite doable.

 

[dkilgo]

Thank you, KREYNOLDS, for the lesson on the DMG, and your interpretation of the afore mentioned text. I do understand what the DMG is stating, but that does not mean that I have to agree with it. As you stated previously, the rules within the DMG are guide lines. So, this leads me to believe that they are to be interpreted in any fashion as long as the effect does not go beyond certain reasonable measures. What those reasonable measures might be are simply laid out in the DMG, or in a person's set of house rules. Hence, I believe that the quickest method for results occurs when one targets the entire square and not an intersecting grid line. But, I will give both methods a try in my own personal play test. Of course, I will be trying these methods out with my players to ascertain the appropriate method for the situation. I will keep you informed.

 

[kreynolds]

Thank you, KREYNOLDS, for the lesson on the DMG, and your interpretation of the afore mentioned text. I do understand what the DMG is stating, but that does not mean that I have to agree with it.

You misunderstand. I wasn't actually trying to get you to see this from my perspective, rather it was more an attempt to get you to see it as the DMG is written. That's all. What you do with it from there, whether or not you use it or create house rules, is up to you.

Also, it wasn't an interpretation. I stated what was in the DMG. Now, my opinions were in there as well, such as why I think that passage is written as such (i.e. ease of placement, accuracy) and why I think it should be followed (i.e. yielding inaccurate area results, areas that could be bigger than they are meant too.)

Here's an example why the DMG suggests using intersecting lines. Antimagic Field is a 10-foot radius emanation (this equates to 20-feet in diameter). If you plop that down in the center of a square, one of two things will happen...

1) Following the majority of effected square rule, you will actually end up with a 25-foot diameter (12.5-foot radius), not a 20-foot diameter (10-foot radius). The text of Antimagic Field states it is a 10-foot radius, not a 12.5. That's pretty much the bottom line there.

2) If you want to stick with the text of Antimagic Field, but you still want to place the origin in the center of a square, you need to adhoc how you determine who is effected in those half-covered squares, for one is automatically effected, your spell area is too big again, beyond what is stated in the spell itself. So, how do you determine who is and is not effect in the half-effected square when the majority of the square is not covered, meaning it is essentially split right down the middle? Adhoc. That's how.

So, if you stray from that passage in the DMG, you not only have to adhoc the placement of spells, but now you have to adhoc every single burst, emananation, ,spread, cone, etc area spell that gets plopped down one the grid.

All I'm saying is that the DMG suggests what it does so that you don't have to adhoc the multitude of spells as they get placed on the grid. So, really, its not so much a question of what does the DMG state, since that's plainly clear, and neither is it a question of what the Antimagic Field spell states, for that is clear as well. Instead, its more a question of "How much time do you have?"

Of course, I will be trying these methods out with my players to ascertain the appropriate method for the situation.

So I guess this means Feuermann will be tapping his foot alot in the coming sessions?

 

[Negative Zero]

i think that starting at a gridline intersection makes no sense because you naturally assume distances from outside of the SQUARE that you and/or the starting point of a spell is in.

take for example, any average human PC holding a dagger or staff. her "area of effect", as it were, is a 5 foot radius around her. if you start that at a gridline the PC can only cover 4 squares, which isn't the case at all. it should be eight.

a 5 foot radius starts at each outside line and corner of the staring point square.

using this same formula, a 10, 15, 30, 100, 1,000 foot radius will start from the same place. and as long as this is consistently done for EVERYONE then it both acurate and fair.

~NegZ

 

[dkilgo]

Okay, I see what you are saying. The intersecting grid line targeting is only an easy mehtod to determine what area a spell might effect. Because, it will take way too much time to ahoc every little thing about spells that might possibly effect an area. Okay...okay...okay...

I sit contemplating what to do next, !#*&.

And, no, Feuerman will not be tapping his foot alot. I was not goingto play test it with that group. Only on a solo...

 

[kreynolds]

The intersecting grid line targeting is only an easy mehtod to determine what area a spell might effect. Because, it will take way too much time to ahoc every little thing about spells that might possibly effect an area.

Exactly. Doing otherwise will take more time, or without adhoc rulings, it will yield innacurate results.

 

[drnuncheon]

Of course, the PHB and DMG are remarkably inconsistent on this topic. The diagrams for meteor swarm are pretty clearly centered on squares, and many of the other diagrams (burning hands, cone of cold) show spells with their origin points, not at the center of a square or at a grid intersection, but at the midpoint of a side.

J

 

[kreynolds]

Of course, the PHB and DMG are remarkably inconsistent on this topic.

Yup.

 

[dkilgo]

So, from everything that has already been posted all the way up to drnuncheon's most recent post, I surmise that the best method of approach might possibly depend on the situation. Depending on the situation and spell one might use one method, and then turn around the next round to use another method. Of course, depending on the situation. Situational placement?