Technical Terms
Aperture |
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A part of the camera that determines the size of the opening where the light enters the camera and hits the sensor. This determines the region of the image that will be in focus and the brightness of the image, like the shutter speed. A large aperture (small f-number) results in a large opening, therefore more light, leading to a brighter image or a shallow depth of field.
Artifacts |
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An observation made on an object (e.g., photo evidence) that is not naturally present resulting from unintentional damage or error in the collection or processing technique.
Class characteristics
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Characteristics that are an intentional or unavoidable characteristic that repeats during the manufacturing process and is shared by one or more other shoe. Examples of class characteristics include footwear outsole and physical size of shoe, these class characteristics establish membership within a specific group.
Digital plane of camera
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Defined by the camera’s sensor’s angle relative to the angle of the substrate being photographed; must be parallel to the substrate’s angle.
Exclusion
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This is the highest degree of non-association between a questioned impression and known source based on sufficient differences observed during the comparison of class and/or randomly acquired characteristics between the questioned impression and the known footwear. in the opinion of the examiner the particular known footwear or tire was not the source of and did not make the impression.
Identification/Inclusion
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The highest degree of association assigned to a questioned impression and known source based on the agreement of class and randomly acquired characteristics when there is sufficient quality and quantity of information.
Individual characteristics
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Characteristics specific to only that piece of evidence and can be used to make an identification based on inclusion/exclusion.
Laterally reversed
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When a 2-dimensional footprint is lifted using the electrostatic lifter onto the mylar film the print gets reversed and must be accounted for when being characterized.
Non-porous |
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A material that does not have open spaces or holes (within), which does not allow air to pass through.
Porous |
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A material having open spaces or holes within which materials and air can pass through.
Shutter speed
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A part of a camera that determines the duration that the light gets to hit the sensor, the faster the shutter speed, the lower the time of exposure, therefore the darker the image.
Substrate |
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The material upon which a fingerprint/footprint impression is deposited through contact. Substrates are often classified as porous or non-porous.
A part of a camera that determines the duration that the light gets to hit the sensor, the faster the shutter speed, the lower the time of exposure, therefore the darker the image.
The outside surface of the sole of the shoe.
The material upon which a fingerprint/footprint impression is deposited through contact. Substrates are often classified as porous or non-porous.
The highest degree of association assigned to a questioned impression and known source based on the agreement of class and randomly acquired characteristics when there is sufficient quality and quantity of information.
This is the highest degree of non-association between a questioned impression and known source based on sufficient differences observed during the comparison of class and/or randomly acquired characteristics between the questioned impression and the known footwear. in the opinion of the examiner the particular known footwear or tire was not the source of and did not make the impression.
A mark left behind from contact between two objects that only has two dimensions to it: length and width, no depth.
A device used to conduct technique used to recover dusty footprints. A mylar film is placed over the print and charged using an electrostatic lifter device. The charged mylar film attracts and adheres the dusty footprint.
Porous materials allow for the absorption of the residues into the matrix of the substrate (e.g., paper, leather, tape, clothing).
Non-porous materials prevent the absorption of the materials and they are deposited on top of the surface through adsorption (e.g., plastic, metal, some tapes).