Height of relief of bust

[expat]

Being an absolute beginner

everything is fascinating and I want as much info as I can get. Received this yesterday (and posted here). I am amazed at the depth the obverse die was sunk. The relief on this coin is, to me, fascinating. I know it wasn't an exact science back then, but even so

 

[Kaleun96]

That's a decent relief! At one point I tried to take measurements of this as it's not quite the same as a coin's thickness in the sense a thick coin doesn't always have a high relief. Though I soon fell down the rabbit hole of how you determine how high something is when there's no intrinsic "ground" to measure from. It seems like a similar problem that you have with measuring mountains in terms of elevation vs prominence: the elevation is measured from sea level but that doesn't necessarily reflect how prominent it is relative to other features around it (hence K2 being the 2nd highest mountain but 22nd in prominence).

But back to coins, as we all know flans are rarely perfectly flan, particularly Greek tetradrachms, which can often be slanted. The edge of a coin can vary from 4mm in one area to 2mm in another. So when laid flat, the distance from the highest point to the lowest point in the fields will be wrong if the plane of the obverse face is not parallel to the surface its sitting on. I'm sure someone could figure out a "proper" way to measure the relief of a coin independent of thickness, if anyone has any ideas let me know! Maybe something like the difference between the maximum height of a coin when laying flat on a surface and the maximum thickness of the edge as measured from a point on each side of the coin that is in the fields (i.e. don't measure from where a portrait might be halfway off the flan and thus make that part of the edge seem overly thick).

[shanxi]

Wait until you start collecting Greeks. Then the Romans will seem flat to you. 

[shanxi]

1 hour ago, Kaleun96 said:

if anyone has any ideas let me know!

You have to draw a line profile (minimum: 3 points), and than interpolate the distance between the flat fields with a straight line. Subtract the highest point of the image (head or figure) from the "virtual" height of the interpolated line below and you get the maximum  height of the relief.

Edited August 9, 2022 by shanxi

[Kaleun96]

32 minutes ago, shanxi said:

You have to draw a line profile (minimum: 3 points), and than interpolate the distance between the flat fields with a straight line. Subtract the highest point of the image (head or figure) from the "virtual" height of the interpolated line below and you get the maximum  height of the relief.

Sorry I lost you at "draw a line profile" 😁 Do you mean to try and draw the profile of the relief from the side-on? Ideally i'm looking for a method that would be fast and easy, like at most taking two measurements with a calliper or similar tool.

Edited August 9, 2022 by Kaleun96

[shanxi]

Apparently, my description was a bit confusing.

 

As I understand it, you want to determine the relief height of a coin that is not exactly flat. Here is an example of a very slanted coin.

black: the coin, red measurement points

 

Edited August 10, 2022 by shanxi

[Kaleun96]

1 hour ago, shanxi said:

Apparently, my description was a bit confusing.

 

As I understand it, you want to determine the relief height of a coin that is not exactly flat. Here is an example of a very slanted coin.

black: the coin, red measurement points

 

Ah that makes sense, thanks! I think you're right that it would give a good estimation of the actual relief, it's a shame that it is somewhat difficult to do in practice and with lots of potential for measurement error due to the number of measurements you need to make/approximate. For example, measuring x1 or x2 requires you to measure from A to C and while finding the spot for A may be easy due to it being at the edge of the devices, pinpointing the highest spot C could be more difficult.