Question for milling and range estimation. When you have an object of known size (height/width) at an unknown distance how do you formulate milling the object if it is positioned at an angle from your direct line of sight and then apply the range estimation formula? (eg. thin, two dimensional stop sign, sitting at a 45° angle)
Milling Known Size Objects question
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I think you can use the bounding box calculation. Somebody please kick my ass if I fucked this up!
In the diagram below, picture your object (stop sign) viewed from above, rotated by amount theta.
Let theta=45º, let y=36" be the width of the object, and x=0 be the (approximate) thickness. Then solve for by, to get apparent width from the given angle:
by = c + d
= x * sin(t) + y * cos(t)
= 0 * sin(45) + 36 * cos(45)
= 0 + 36 * 0.71
= 25.56"
Then mil as usual using apparent width as known width.
In the diagram below, picture your object (stop sign) viewed from above, rotated by amount theta.
Let theta=45º, let y=36" be the width of the object, and x=0 be the (approximate) thickness. Then solve for by, to get apparent width from the given angle:
by = c + d
= x * sin(t) + y * cos(t)
= 0 * sin(45) + 36 * cos(45)
= 0 + 36 * 0.71
= 25.56"
Then mil as usual using apparent width as known width.
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I would just use the height, rather than the width.
If I understand you correctly, it really doesn't matter how thick or thin the target looks, what matters is how tall it is. A stop sign could be turned a full 90 degrees from you, and it wouldn't matter. The stop sign is still (X) feet tall.
If you are talking about the sign leaning left to right at 45 degrees, then just turn your rifle 45 degrees and align your vertical crosshair with it and measure the mils.
Or, maybe your question is harder than I think it is.
If you are talking about the sign leaning left to right at 45 degrees, then just turn your rifle 45 degrees and align your vertical crosshair with it and measure the mils.
Or, maybe your question is harder than I think it is.
If you can estimate the angle, you multiply the object size by the cosine of the angle to get the apparent size, then use that.
cos of 45 degrees is .7, so a 36" sign rotated 45 degrees would be .7 x 36, or 25.2". Less complicated that the bounding box and plenty precise enough.
This problem occurs rarely, as stated above, height then becomes the primary option, if tilted towards or away use width. If it's both tilted and turned, don't worry unless both angles exceed 20 degrees.
OR
Range some other nearby object.
My solution? I ping it with a Vector IV , but I'm pretty lazy.
cos of 45 degrees is .7, so a 36" sign rotated 45 degrees would be .7 x 36, or 25.2". Less complicated that the bounding box and plenty precise enough.
This problem occurs rarely, as stated above, height then becomes the primary option, if tilted towards or away use width. If it's both tilted and turned, don't worry unless both angles exceed 20 degrees.
OR
Range some other nearby object.
My solution? I ping it with a Vector IV , but I'm pretty lazy.
Yes, the question is generally assuming an object pivoted on its Y axis right or left (like a door opening or closing) or rotating on the X axis, either way. I understand you can always mil the side that is face forward, but it’s something I’ve wondered how to attack the problem if it ever arose and didn’t have anything else to mil.
Better to have a working knowledge of how to attack the rare/impossible situations that may arise when you have nothing else to work with.
Thanks for the info, everyone.
Better to have a working knowledge of how to attack the rare/impossible situations that may arise when you have nothing else to work with.
Thanks for the info, everyone.
I always thought the whole idea behind "milling" the target was to be able to quickly estimate distance in the field without having to use anything more than a pencil and paper, or a 98 cent calculator. I wouldn't overthink it. Especially, if you don't know the exact angle the target is leaning. I would just parallel the vertical cross hair to the target and measure the mills tall. Then, work the basic equation: (yards tall * 1000) / scope mills tall = distance to target.
The vertical dimension would work the best, like state above.
If you had to use the horizontal distance a quick reference can be your wind chart. You chart turns angles into the perpendicular values. This will give you the multiplier.
45 deg = .707
15 deg = .96
If you had to use the horizontal distance a quick reference can be your wind chart. You chart turns angles into the perpendicular values. This will give you the multiplier.
45 deg = .707
15 deg = .96
As others have said: the vertical distance is unchanged. A square target will appear to be a rectangle.
If you want to calculate the apparent size you could use the formula x=h*cos(theta).
You use the true horizontal size to figure out the apparent horizontal size. For example, if you have a 36 inch x 36 inch steel target that is viewed at a 45 degree angle the apparent horizontal size will be x=36*cos(45) which is 25.46 inches. The same applies to meters, centimeters, yards, etc. Just keep your units consistent.
You could do the same for a target that is leaning against a wall or something. In that case it would be y=h*sin(theta)
Once you have the apparent size, use that value in your range estimation.
If you want to calculate the apparent size you could use the formula x=h*cos(theta).
You use the true horizontal size to figure out the apparent horizontal size. For example, if you have a 36 inch x 36 inch steel target that is viewed at a 45 degree angle the apparent horizontal size will be x=36*cos(45) which is 25.46 inches. The same applies to meters, centimeters, yards, etc. Just keep your units consistent.
You could do the same for a target that is leaning against a wall or something. In that case it would be y=h*sin(theta)
Once you have the apparent size, use that value in your range estimation.
Learning to ret range is not hard, but never forget that target color an lighting angle adds a different deduct % based upon an YOUR EYES. The smaller the target an greater the glossiness of same, can make the error percentage to the point of missing the target depending range an chambering. Flat/subdued color targets are easy, but add other colors like bright yellow/reds/orange, or any type of florescent an ret ranging can go wrong quick, unless you know Your deduct percentage.
