FINAL EXAM Flashcards
(26 cards)
Why utilize a “tent” when photographing evidence close up?
It will give you “even” illumination without any shadowing
What should your “white balance” setting be while using the tent’s built-in lighting?
Daylight or flourescent
What can you do to insure your “white balance” is correct when photographing through a microscope?
Place a blue filter in the light path or change your white balance setting to tungsten
What advantages is there to utilizing a “macro” lens when taking close-up photographs?
you can get closer to your subject (producing a larger image) and still be in focus
List 3 types of macrophotography accessories.
diopters, extension tubes, bellows, reversing rings, and macro lenses
Types of photogrammetry
- Perspective grid photogrammetry
- perspective disc photogrammetry
- natural grid photogrammetry
- reverse projection photogrammetry
- computer aided design (CAD) software (rhinoceros)
Why you may use photogrammetry
- lots of measurements needed to be made at a scene
- reconstruction analysis needs to be preformed later
- equipment or manpower not available
- short release time requirement for a crime scene
- minor scene that could become a major scene
- insurance shots (just in case!)
UV Light
- used to enhance to create contrast through florescence
- uses light/energy below 400 nm
How is florescence created?
excitation of a subjects electrons when UV energy is added
How is contrast created as a result of fluorescence
Because of the excitation of a subjects electrons, they are in a higher state of energy or orbit, and this causes potential evidence to enter the visible light range of the EMS. Thus creating constrast
UV Light applications
- forgery and document alterations
- fibers and other trace evidence
- semen, blood, or any other bodily fluids
- bruises or bite marks
- gun power residue
- fingerprint enhancements
Stages of brusing
0-2 days: oxyhemoglobin (red)
2-5 days: deoxyhemoglobin (blue)
5-7: biliverdin (green)
7-10: bilirubin (yellow)
10-14: hemosiderin (brown)
SICAR
Shoe imprint capture and retrival
IR photography
Like UV, but applies light of 700 nm or higher to evidence; directly apply to the evidence or reflect the IR light, but filters will be needed to block all visible light from entering the camera and only view the IR light.
IR light application
- enhancement of tattoos
- document examination and forgery investigations
- gunshot residue
- bloodstain evidence
UV/IR Documentation
alternate lighting may make objects fluoresce or be more visible against their backgrounds
Copyright
Rights over an artistic work that gives whoever is copywriting exclusive rights to make, sell, and distribute, and adapt the original work.
Doctored Image
transformation or alteration of a photograph, can be seen as skillful art or unethical practice.
How to tell if an image has been altered
- Look at the metadata (EIFX data) which can determine what camera the photo was taken on, at what time and location information
- check JPEG compression quality
- look for warping or digital distortion
- shadow discrepancies/inconsistent lighting
- unnatural colors
- poor removal of objects
- repeated or copied patterns
- no depth of field within image
Analysis tools for digital images
- forensically there are free websites and tools (error level analysis, metadata extraction, clone detection, JPEG quality, etc.)
- FotoForensics (free tool that gives access to tools used in digital forensic analysis)
- Amped software
4.
Public Images
Images that are free for public use that individuals can use without worrying about copyright issues.
When a bloodstain is found on a pair of blue jeans and the photographer wishes to increase the contrast of the image by making the red bloodstains darker in the photograph, which colored filter would be the best choice?
A. Red
B. Blue
C. Green
D. Yellow
B. Blue
When a bloodstain is found on a section of green carpet and the photographer wishes to increase the contrast of the image by making the green carpet lighter in the photograph, which colored filter would be the best choice?
A. Red
B. Blue
C. Green
D. Orange
c. Green
Blood _______ UV light.
A. Reflects
B. Absorbs
C. Fluoresces with
D. Refracts
B. Absorbs
