Monday, September 24, 2018

Three-dimensional reconstruction of Roman coins from photometric image sets

Three-dimensional reconstruction of Roman coins from photometric image sets”, a 2017 Journal of Electronic Imaging paper by Lindsay MacDonald, Vera Moitinho de Almeida, and Mona Hess.

The present study combined two datasets representing the surface topography of the two Faustina coins (Fig. 1). First, they were scanned by a 3-D color laser scanner, producing a point cloud of the surface shape. Second, they were photographed in an illumination dome with directional lighting. The two representations were combined to produce a digital elevation map (DEM) of each coin with the accuracy of the scanner and the fine detail of the photography.

Tuesday, September 18, 2018

The Insane Million Maker Master Counterfeiter

Good documentary storytelling on counterfeiting: Snap Judgement recently made a 22 minute segment about Frank Bourassa, a Canadian who counterfeited a quarter of a billion US dollars in twenties in 2009.

I calculate that $200,000,000 in $20 bills would weight 10 tons and would completely fill a 12' moving van.

Friday, September 07, 2018

NGC population reports for graded ancient coins

Catalogers of high grade modern coins often boast about coins having only a few specimens, or even no specimens, known in a higher grade.

Ancient coin catalogers will sometimes say "finest known" but they rarely say things like "only a population of 43 coins better".

On NGC's slab verification pages, for example, there are no population reports comparable to modern coins. That page says "Total Graded by NGC: Not Available".

Yet I noticed the Heritage Auctions web now includes NGC Ancients population reports. I noticed this watching their Long Beach auction yesterday. Here is an example from a recent Heritage online-only auction: . The auction listing displays the slabbed population with the grade of the current lot highlighted in yellow.

Here is the owl population as of September 7th 2018:

The auction house gives an NGC population report and includes the count ranked star (= "impressive"). They don't mention "fine style" or "test cut" or the x/5 ratings. This particular lot has a huge test cut that doesn't make it into the numerical chart.

I was curious to see the single starred "Choice MS" example in the above population report. It is, and it sold for $36k last month.