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FIVS 210 > EXAM 2 > Flashcards

EXAM 2 Flashcards

1
Q

Alphonse Bertillon

A

Discovered anthropometry; made the first systematic attempt at personal identification; method was based on 2 premises: the dimensions of the human-bone system remain unchanged from the age 20 and no two individuals have the same measurements at the 11 different locations chosen.

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2
Q

anthropometry

A

Began in France 1883; study of the measurements of the human body and its proportions; helped convict persons

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3
Q

Purposes of crime scene photography

A
  1. Record details of the scene and its surrounding conditions as is/ original condition
  2. Document initial appearance and location of physical evidence with respect to the crime scene
  3. provide investigators, witnesses and others with permanent visual records.
  4. Refresh memory of crime scene
  5. review particular details
  6. provide evidence for forensic comparison purposes
  7. document if an injury as occurred
  8. convey information in a court room
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4
Q

Admissibility of evidence is based on what 3 qualifications

A
  1. must be relevant to the issue of the case
  2. must be a true and accurate representation of the crime scene
  3. probative value (usefulness / relevancy) must outweigh prejudicial effect of photographs; does the potential benefit of proving the facts in the photograph outweigh any potential negative impact it could have on the fairness of the trial
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5
Q

Capturing quality crime scene photos include:

A

Photos must be:
1. correctly exposed
2. maximum depth of field
3. be in focus and distortion free

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6
Q

Documenting the crime scene

A

need photographs in long (overall), medium (mid-range), and close-ups

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7
Q

Long (overall) photographs

A

purpose is to establish to an overall view of the crime scene location an potential evidence; photos can be overlapped to make connections; capture the scene as originally found

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8
Q

Outdoor long photographs

A
  • photograph landmarks
  • aerial photos of scene and surrounding area
  • photos at all angles
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9
Q

indoor long photographs

A
  • photograph all four corer of the room to show the layout
  • wide angle lens may be used in confined spaces to get complete coverage
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10
Q

Medium photographs

A
  1. establishes location of potential evidence with respect to other items at the scene
  2. transitions viewer from distance standpoint to a move involved POV
  3. evidence becomes more readily identifiable
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11
Q

Close up photographs

A

Used to clearly identify evidence and establish exact location; fill frame with evidence
- they should be photographed w/ and w/o scale
- photographs at 90%

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12
Q

Markers and placards

A
  • aid to viewer recognition, location and orientation of evidence
  • always take one photograph with and without the marking and measurement device
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13
Q

Scales

A
  • establish the size of the evidence
  • assist in forensic comparisons
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14
Q

Cardinal Rules of Crime Scene photography

A
  1. fill the frame
  2. maximize the DOF
  3. keep the film plane parallel
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15
Q

Rules of investigative photography

A
  1. if its worth looking at its worth photographing
  2. photograph everything before you move or alter it
  3. document w/ 3 shots: long, medium and close-up
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16
Q

What should be photographed?

A
  1. location of witness, perp, objects of interesst and any witnesses when you arrive on scene
  2. POV of witnesses, victims perpertrators, etc.
  3. injury or damage to people or items
  4. immplements or contraband
  5. debris, tire tracks, tool marks, fingerprints, palm prints, and footprints
  6. likely exit or entrance routes
  7. overall shots of the scene
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17
Q

handling the camera (tripod)

A
  • focus 1/3 of the way to get max DOF
  • use tripod if feasible or anything to support the camera
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18
Q

Photograph log purposes.

A

two purposes:
- recording general information about the case (help jog memory and explain lighting conditions)
- recording specific information about each photograph you take

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19
Q

Case Identifier Tag

A

First frame that is photographed at the crime scene is usually the Case ID tag. It tells information such as the case #, photographer’s name, investigators name, etc.
- easy way to identify a roll of film once processed
- decision on whether or not to photograph a Case ID tag is up to the photographer

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20
Q

What is the purpose of taking evidence photos with and without a scale?

A

A scale is utilized to capture important dimension information and a photograph without the scale is for court purposes to document the scene without any “modifications”

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21
Q

With respect to photographs, what does the phrase “true and accurate representation” mean? Explain as if you are speaking to a jury.

A

photos being presented must truly represent the crime scene as accurately as possible

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22
Q

You are asked to determine the size of an item of evidence from a photo. Explain the process of doing this to a jury.

A

By utilizing the scale in the photo, a relative dimension can be obtained on any item in the image. The easiest way to do this is to enlarge the image and print the scale to its “natural size.”

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23
Q

Inverse square law and how it relates to intensity

A

I = 1/d^2; farther from the flash, the less light

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23
Q

What are two considerations when utilizing a scale in your photographs?

A
  1. The scale should be at the same height as your subject.
  2. The scale should be a similar “shade” as your subject (black for dark backgrounds, ans white for light backgrounds, grey for neutral backgrounds).
  3. Your camera film plane should be parallel to your subject (or your lens axis should be perpendicular to your subject)
  4. The scale you use should be an appropriate length for your subject (don’t use a six-inch ruler for a tire track print).
  5. Take a picture of the item (at a crime scene) before you place a scale in the picture (shows the scene as you found it).
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24
Q

built in flash

A
  • most convenient, but least powerful
  • inconveniently placed can cause red eye or macro-photography coverage problems
  • may be used to trigger other electronic flash (EFUs)
  • may be used for fill outdoors
  • built in flash must be diffused to minimize inconsistency of exposure for macro-photography
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25
Q

Flash synchronization

A
  • built in flash is timed to the exposure by camera circuits
  • accessory flash must be connected to the exposure
  • no upper speed limit for flash synch.
  • the speed of the exposure must be slow enough to allow for the benefit of the flash
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26
Q

Fill Flash

A
  • always adjust the flash exposure, not the camera exposure, when using EFU
  • fill flash should not change the overall exposure
  • it should only lighten the shadows and reduce image contrast
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27
Q

Bounce Flash

A

the optimal angle between the flash and bounce surface. Aiming the EUF at the ceiling or walls in order to “bounce” the flash

28
Q

Flash Diffuser

A

Small cut piece of plastic that is used to minimize reflections of the flash

29
Q

Painting with light

A

Camera shutter is locked open in the “bulb” setting.
- shutter will remain open as long as the button is pressed
- cable locks can be used to keep it open and photographer can take their hands off the camera
f-16 gives an adequate depth of field for large outdoor scenes

30
Q

How to paint with light

A
  • Hold the flash as high as possible
  • always point the flash at the subject, not at the camera
  • when you have completely covered the area, turn to the camera and gently close the shutter.
31
Q

Why utilize a “fill-flash” technique?

A

To lighten up any “dark” or “shadowy” areas

32
Q

Why utilize a “bounce-flash” technique?

A

To avoid “hot spots” in your image

33
Q

Why is it important to use a flash (from at least 3 different angles), when photographing a three-dimensional print?

A

When you direct light at oblique angles, you get better 3D images, but you may produce some shadowing, which could mask detail.

34
Q

Explain what is meant by “examination quality” photographs? Why is it important to take “examination quality” photographs of a footwear print (or fingerprint) prior to lifting or casting?

A

Examination Quality” photographs are photos taken at the proper resolution, angle, lighting, and scale to allow for additional forensic comparisons. Lifting or casting may modify or fail to replicate the prints sufficiently, therefore examination quality photos should be taken prior to these techniques, to assist with or without additional collection procedures, during the initial comparison step.

35
Q

Handling the camera (hand shakes)

A

when holding a camera by hand you’re gonna need a shutter speed of 1/60s or faster to compensate for shaking. Tripods are useful for closeups where hand-shake tends to be magnified

36
Q

tripod components

A
  1. pan-tilt tripod head
  2. tripod head mount
  3. center column locking knob
  4. grips
  5. center column
  6. counter weight holder
  7. leg extension flip locks
37
Q

Examination quality photographs using a tripod

A

mount camera on tripod and position directly over impression with film plane parallel to impression

38
Q

Angle of camera tripod

A

90 degrees

39
Q

SWGIT

A

Scientific Working Group Imaging Technology

40
Q

Category 1 images

A

documentation images used to record a time, place or event

41
Q

Category 2 images

A

evidentiary images used for scientific analysis and comparison

42
Q

Bits of DATA

A

1 or 0s

43
Q

Metadata

A

Information embedded within an image file that provides information detail.

44
Q

Best practices in digital image enhancement

A
  • start with best possible image
  • preserve original image
  • make enhancements to a copy
  • be able to authenticate both original and enhanced
  • maintain enhancement history
  • follow standard operating procedure that defines the process from when the digital image is acquired to when it is presented in the courtroom.
45
Q

Enhancement of category 1 vs. category 2 images

A

category 1: detailed enhancement history is history is not required, instead agency can specify in its SOP what functions were used to enhance the image

category 2: detailed enhancement history is required and must be maintained for all images. basic techniques must also be documented bc these techniques can affect the results when used with enhanced techniques on the same image

46
Q

Dynamic range

A

range of values between light and dark

47
Q

Clipping

A

loss of detail in a photo when images are lost due to the shadows or highlights being too bright or too dark for the camera to capture

48
Q

FFT

A

Fast Fourier Transform; repetitive background patterns such as dots or lines often obscure detail in fingerprints or other impressions.

49
Q

How to start / open history log

A
  • Open Photoshop CS5
  • Go to Edit -> Preferences -> General
  • Check History Log Box
    (Save Log Items to: “Both” a Metadata File and a Text File. Make a “Photoshop Edit Log” )
  • Change “Edit Log Items” to “Detailed”
50
Q

Histogram Analysis

A

abundance of a certain value will go towards the edges of the scale to indicate a loss of information.
- under exposed image will have a bulk of the values on the dark side while an overexposed image will have most of the values on the light side.

51
Q

Macrophotography accessories

A
  • diopters (close-up filter set)
  • extension tubes
  • reversing rings
  • macro lenses
52
Q

Macrophotography lighting

A
  • ring flash
  • macro-flash
  • flash direction
  • flash intensity
  • reflection
53
Q

Magnification

A

camera to subject distance, the relationship between the size of the in focus subject’s projection on the imaging sensor and the subject’s size in reality.
- the minimum focusing distance for a typical 50mm lens is about 18”

54
Q

The rules of evidence provide two primary legal principles for digital image processing. Processed digital images may be used if…?

A

nothing material or essential has been added to the original image

55
Q

When using the Levels function to adjust the shadows and highlights of an image, what should you be careful of?

A

clipping the image

56
Q

Why is it sometimes necessary to “resize” or “calibrate images 1:1” when doing comparison work?

A

the camera has no idea how large the captured are is, it knows only that the area consists of a certain amount of horizontal and vertical pixels, so it may be necessary to resize or calibrate the image.

57
Q

The “enhancement” process should be defined to allow only commonly accepted image processing techniques that improve the visualization (quality) of the image without adding or removing features (content) that were not present when the digital image was captured. Generally, is this statement True or False?

A

True

58
Q

With “Category 2” images, you should maintain the sequence of the steps used during the image enhancement process, and you should also record the settings and parameters used for each step. This information must be sufficiently detailed so that a person with comparable skills, training, expertise, and experience could repeat the process and achieve a comparable result. Generally, is this statement True or False?

A

True

59
Q

Diopters

A

Close up filter set; decreases minimum focus making the size of the subject in the viewfinder bigger
- common values: +1, +2, +4
- can stack filters to increase magnification
- because they are glass, stack more than one and the softer the focus of the subject becomes

60
Q

Extension Tubes

A
  • expensive
  • get in close without distorting the image
  • produces sharper images compared to diopters
  • shutter speeds and exposure will be effected in images because it takes the light longer to travel through the lens and reach the camera sensor
61
Q

Reversing rings

A
  • allows you to mount your lens on your camera backwards
  • makes the lens act like a magnifying glass
  • cheaper alternative to other methods
  • rings are camera specific and the thread of you filter needs to match
62
Q

Macro lenses

A
  • lens that specifically allow you to focus extremely close to a subject so it appears larger in the viewfinder
  • “true” macro lenses are able to project subjects onto the camera’s sensor at 1:1 reproduction/magnification ratio.
63
Q

Macro flash and ring flash

A
  • assist in separating the flash from the camera’s lens
  • reduces the red-eye and unwanted reflections
  • can potentially cause addtional shadowing/lighting if not monitored properly
  • utilize the flash sync cord to use these devices and properly illuminate the subject
64
Q

Flash Aiming

A

Aim at the subject
- minimization of shadows
- separation from background

65
Q

Oblique lighting

A

accentuates the surface details while built in flash flattens the light

66
Q

Axial Lighting

A
  • light emanates from a source on the same axis as the image capture by the camera
  • the lighting is very flat and creates no oblique shadows
  • useful for shiny and high-relief subjects
67
Q

Tent lighting

A
  • enclosed reflector for imaging subjects with shiny and curved surfaces
  • do not use colored materials for diffusers
68
Q

Image magnification

A

Macro-photography has a limited range of magnification
The higher the magnification the:
- more difficult the project
- the less DoF
- The more light necessary

FIVS 210 (3 decks)

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