2D/3D Topography Comparisons of 10 

Consecutively Manufactured Chisels and Punches 

Through the Cross Correlation Function

A. Zheng, J. Villanova, Johannes Soons, R. Thompson

National Institute of Standards and Technology

1

November 28, 2012
Disclaimer

Certain commercial equipment, instruments, or materials 

are identified in this report in order to specify the 

experimental procedure adequately. Such identification is 

not intended to imply recommendation or endorsement by 

the National Institute of Standards and Technology, nor is it 

intended to imply that the materials or equipment identified 

are necessarily the best available for the purpose.

2
Contents

• Project Goal and Motivation

• Sample Preparation

• 10 Consecutively Manufactured Chisels

• Chisel – Striated Toolmark Creation

• Chisel – Measurement and Analysis

• 10 Consecutively Manufactured Punches

• Punch – Impression Toolmark Creation

• Punch – Measurement and Analysis

• Conclusions

3
What is a Toolmark?

4

WI Department of Justice lockpickingforensics.com

• Almost anything can create a toolmark as long as the tool is 

harder than the surface it’s being used on. 

• The surface topography of the tool is imparted onto the 

surface. The resulting toolmark can be later used to identify 

the tool. 
MO Dept. Of Public Safety Leica Microsystems

Traditional Comparison Microscopy
Project Goal and Motivation

• Consecutively manufactured tools have a high likelihood of 

containing sub-class characteristics which can lead to 

false positives. It’s considered the most difficult 

comparison. 

• Our goal is to provide objective mathematical comparisons 

of toolmarks created by 10 consecutively manufactured 

chisels (striated toolmarks) and punches (impression 

toolmarks). 

• Can consecutively manufactured tools still be uniquely 

identified from the toolmarks that they created? 

6
Sample Preparation

• The surface that the tools will be marking is a soft copper 

plate. The copper plate has been sanded with 1000 grit 

sand paper and polished using a metal polish. 

• The surface preparation ensures that there are no 

directional striations present on the surface that can be 

confused with the created toolmarks. 

7

Ra ~ 70 nm Ra ~ 20 nm
10 Consecutively Manufactured Chisels

8

• 10 consecutively manufactured chisels from Western 

Forge (supplier to Craftsman Tools) 

• 2 known marks per chisel to establish known match/nonmatch distributions 

• Hide chisel identities, 2 more marks per chisel (Unknown 

set)

• Identify unknown toolmarks using CCFmax
Chisel – Striated Toolmark Creation

9
Chisel – Striated Toolmark Creation
Chisel – Striated Toolmark Creation

11

Toolmark

Break-in 

Region
Chisel – Measurement and Analysis

12

• Z-resolution: 0.8 nm 

• X-Point spacing: 0.25 μm

Taylor Hobson Ltd

• Nominal Stylus Tip Radius: 2 μm

• Trace Length: 25 mm
Chisel – Measurement and Analysis

13

Chisel 6-1

Chisel 6-2
Two Dimensional Cross Correlation Function

14 Rq(A)Rq(B)

CCV(A,B, )

CCF(A, B, )



 

2

1

1

2

2

1

0

2

1

( )

1



























  

N

i

i

L

Z

N

Z x dx

L

Rq 











 





Z x Z x d x

L

L

L L

( ) ( )

1

CCV(A,B, ) lim A B

/ 2

/ 2

 
Known Toolmark Distribution

15

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Percentage

CCFmax %

56.4 %

μ= 16.51

σ= 3.11

μ= 87.10

σ= 10.25
Unknown Toolmark Distribution

16

0

10

20

30

40

50

60

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Percentage

CCFmax Score

μ= 16.60

σ= 3.06

μ= 88.71

σ= 8.60
Unknown Toolmark Identification

17

CCFmax

%
10 Consecutively Manufactured Punches

18

• 10 consecutively manufactured punches from Western 

Forge (supplier to Craftsman Tools) 

• 2 known marks per punch to establish known match/nonmatch distributions 

• Hide punch identities, 2 more marks per punch (Unknown 

set)

• Identify unknown toolmarks using CCFmax
Punch – Impression Toolmark Creation

19
Punch – Impression Toolmark Creation

20
21

Punch – Impression Toolmark Creation

Known Marks

Unknown Marks
Punch – Measurement and Analysis

22

Parameters for data 

collection:

• 10 x objective

• Z direction step size: 0.2 μm

• Lateral Resolution: 3.125 μm

• Measured Dimension: 4.8 mm

x 4.8 mm
23

Punch – Measurement and Analysis

Filter Parameters

Apply Gaussian filter with:

λL = 400 μm

λS = 40 μm
Three Dimensional Cross Correlation Function

24

2

1

1 1

2

2

1

/ 2

/ 2

/ 2

/ 2

2

( , )

1

( , )

1































   

   

M

k

N

j

L

L

L

x y L

Z j k

MN

Z x y dxdy

L L

Sq

x

x

y

y

















    

 



/ 2

/ 2

/ 2

/ 2

y A B

( , ) ( , )

1

ACCV(A, B, , ) lim

y

y

x

x

x y

L

L

L

L

x y

x y

L L

x

Z x y Z x y dxdy

L L

   

Sq(A)Sq(B)

ACCV(A, B, , )

ACCF(A, B, , )

y

y

 

 

x

x


Punch – Measurement and Analysis

• Final results of this study will be published in 2013. 

• Below is an example of a matching correlation. 

25

ACCFmax: 95.82%
26

Example of a non-matching correlation. 

ACCFmax: 13.38%
Conclusions

• 10 Consecutively Manufactured Chisels

• The statistical distribution between the known matching and 

known non-matching are clearly separated with no overlap. 

• All 20 unknown striated toolmarks were correctly identified 

back to the chisel that created them. 

27

• 10 Consecutively Manufactured Punches

• To be determined
Thanks for your attention!

Questions?

alan.zheng@nist.gov

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