By: Eduardo Maldonado Cuevas
Judicial Expert
Traffic Accident Reconstruction Analyst
Forensic Photographer and Infographic Artist
Active Member of the College of Professional Experts of Chile A.G.
Currently, in traffic accident investigations, experts in traffic accident reconstruction consider video footage from cameras on public roads a primary element of the investigation (they even define it as fundamental support that leaves no room for doubt). This includes footage from monitoring cameras installed on streets, highways, and roads, as well as cameras installed in shopping centers, buildings, and private residences.
Traffic accident investigators currently rely on this undeniable evidence to perform the corresponding analyses and calculations as infallible proof; HOWEVER:
While this video evidence appears irrefutable at first glance, the analysis of such visual evidence should not be taken lightly, for the reasons explained in the following paragraphs.
A. First, it must be considered that the video footage received by these traffic experts comes from copies of the original videos, which would be correct. However, in other cases, it is a recording of an original recording, captured by a cell phone or other device. In this latter case, the quality of this video evidence may be poor, it may have lower resolution, fewer frames than the original, and may have frame skips that distort the video sequence.
Therefore, in this latter case, this video evidence should be completely discarded for the analysis of these studies, analyses, and speed calculations.
B. If the evidence is an original copy, several important aspects must be considered for the analysis of the incident The traffic incident being investigated involves several fundamental factors, including those mentioned below:
i. The angle of the camera recording the event.
ii. The visibility of the vehicle(s) involved in the traffic incident.
iii. The absence of obstacles that would obstruct a clear view during the event.
iv. The movement of vehicles.
v. The lighting conditions at the location.
vi. The light reflection from the vehicles if it is nighttime and the light reflection on the roadway.
vii. The existence of control or reference points on the roadway that can be used to measure the entry and exit points of a vehicle over a given distance.
C. This analysis of the "Original Copy" video camera footage must be thorough: the following parameters must be obtained from it:
i. The number of frames in the video ("a given number of frames is contained within one second (e.g., 30.00/1 = 30 frames per second)").
ii. That the video includes a time counter that displays the date, hour, minutes, and seconds.
D. There are different ways to calculate speed using this video camera system, of which I will only mention two, which provide a general idea of how to accurately determine a given speed.
A. By Reference Points
For this method, we will use a pair of existing reference points on the roadway at the scene of the incident; if none exist, we will look for reference markers that are perpendicular to the street or road within the camera's field of view, which will be designated as points A and B (A for entry and B for exit).
These points can be lines on the pavement, pedestrian crossings, distances between posts, etc. (It is important to note that these control points must be on the trajectory line of the vehicle whose speed is being calculated).
These reference points will be measured first as seen and located in the video, and then these same points will be measured at the scene of the incident during the on-site investigation.
In short, the time it takes for a vehicle to pass between point A and point B will be measured. At the specified distance, the calculation would be:
Example:
Distance in meters d= XXXXXXX
Speed Frame rate SFR =XXX
Number Frame rate nfr = XXX S= 3.6 D*sfr S
Nsf
S= 2.95* 30f/s= 1.83 M/P
B. By Vehicle length or Wheelbase 7
This method is basically similar to the previous one, but now we will use a distance that will be the length or wheelbase (distance between the front and rear axles) of the vehicle, and we will measure the time it takes to pass a specific reference point. In this case, we will use only one reference point, especially if it is located on the road surface along the trajectory of the vehicle being examined. The time it takes to pass this point will be measured.
For this method, we will need the technical specifications of the vehicle in question to obtain its length or wheelbase. Once the control point where the vehicle passes has been determined, the distance between the front and rear axles of the vehicle's tires will be measured.
Distance of Wheelbase dwb= XXXXXXX
Speed Frame rate SFR =XXX
Number Frame rate nfr = XXX V= 3.6 dwb*Sr
Srn
V= 3. 6 3*30 s/f = 28.760 m/p
7
If a margin of error exists, it should not exceed +/- 5%. The difference between the two calculations lies in the fact that the first is calculated using two fixed reference points, while the other method is based on the event itself, which passes through a single fixed reference point. There are no differences in the results.
REFERENCE
The information presented is based on the in-person course conducted in 2019, entitled "METHODOLOGY IN SPEED CALCULATIONS USING VIDEO CAMERAS," which was taught by the OIAT (Office of Traffic Accident Investigation) of the Ecuadorian Traffic Police, and instructed by Major Henry Palacios Macias.
Judicial Expert
Traffic Accident Reconstruction Analyst
Forensic Photographer and Infographic Artist
Active Member of the College of Professional Experts of Chile A.G.
Currently, in traffic accident investigations, experts in traffic accident reconstruction consider video footage from cameras on public roads a primary element of the investigation (they even define it as fundamental support that leaves no room for doubt). This includes footage from monitoring cameras installed on streets, highways, and roads, as well as cameras installed in shopping centers, buildings, and private residences.
Traffic accident investigators currently rely on this undeniable evidence to perform the corresponding analyses and calculations as infallible proof; HOWEVER:
While this video evidence appears irrefutable at first glance, the analysis of such visual evidence should not be taken lightly, for the reasons explained in the following paragraphs.
A. First, it must be considered that the video footage received by these traffic experts comes from copies of the original videos, which would be correct. However, in other cases, it is a recording of an original recording, captured by a cell phone or other device. In this latter case, the quality of this video evidence may be poor, it may have lower resolution, fewer frames than the original, and may have frame skips that distort the video sequence.
Therefore, in this latter case, this video evidence should be completely discarded for the analysis of these studies, analyses, and speed calculations.
B. If the evidence is an original copy, several important aspects must be considered for the analysis of the incident The traffic incident being investigated involves several fundamental factors, including those mentioned below:
i. The angle of the camera recording the event.
ii. The visibility of the vehicle(s) involved in the traffic incident.
iii. The absence of obstacles that would obstruct a clear view during the event.
iv. The movement of vehicles.
v. The lighting conditions at the location.
vi. The light reflection from the vehicles if it is nighttime and the light reflection on the roadway.
vii. The existence of control or reference points on the roadway that can be used to measure the entry and exit points of a vehicle over a given distance.
C. This analysis of the "Original Copy" video camera footage must be thorough: the following parameters must be obtained from it:
i. The number of frames in the video ("a given number of frames is contained within one second (e.g., 30.00/1 = 30 frames per second)").
ii. That the video includes a time counter that displays the date, hour, minutes, and seconds.
D. There are different ways to calculate speed using this video camera system, of which I will only mention two, which provide a general idea of how to accurately determine a given speed.
A. By Reference Points
For this method, we will use a pair of existing reference points on the roadway at the scene of the incident; if none exist, we will look for reference markers that are perpendicular to the street or road within the camera's field of view, which will be designated as points A and B (A for entry and B for exit).
These points can be lines on the pavement, pedestrian crossings, distances between posts, etc. (It is important to note that these control points must be on the trajectory line of the vehicle whose speed is being calculated).
These reference points will be measured first as seen and located in the video, and then these same points will be measured at the scene of the incident during the on-site investigation.
In short, the time it takes for a vehicle to pass between point A and point B will be measured. At the specified distance, the calculation would be:
Example:
Distance in meters d= XXXXXXX
Speed Frame rate SFR =XXX
Number Frame rate nfr = XXX S= 3.6 D*sfr S
Nsf
S= 2.95* 30f/s= 1.83 M/P
B. By Vehicle length or Wheelbase 7
This method is basically similar to the previous one, but now we will use a distance that will be the length or wheelbase (distance between the front and rear axles) of the vehicle, and we will measure the time it takes to pass a specific reference point. In this case, we will use only one reference point, especially if it is located on the road surface along the trajectory of the vehicle being examined. The time it takes to pass this point will be measured.
For this method, we will need the technical specifications of the vehicle in question to obtain its length or wheelbase. Once the control point where the vehicle passes has been determined, the distance between the front and rear axles of the vehicle's tires will be measured.
Distance of Wheelbase dwb= XXXXXXX
Speed Frame rate SFR =XXX
Number Frame rate nfr = XXX V= 3.6 dwb*Sr
Srn
V= 3. 6 3*30 s/f = 28.760 m/p
7
If a margin of error exists, it should not exceed +/- 5%. The difference between the two calculations lies in the fact that the first is calculated using two fixed reference points, while the other method is based on the event itself, which passes through a single fixed reference point. There are no differences in the results.
REFERENCE
The information presented is based on the in-person course conducted in 2019, entitled "METHODOLOGY IN SPEED CALCULATIONS USING VIDEO CAMERAS," which was taught by the OIAT (Office of Traffic Accident Investigation) of the Ecuadorian Traffic Police, and instructed by Major Henry Palacios Macias.
Newsletter# 2 GJ Forensics ,Llc
5/27/2023
Greeting, all GJ Members and lovers of criminal investigation / Forensic investigation. This is a newsletter # 2 made by Mr. Tomas Sevilla delegate member from GJ Forensics for Europa. The contents are:
1 Statement of intentions…………………………………………………….. 4
- Intra-Family Terrorism ………………………………………………….. 4
3 Statements of Intents……………………………………………………………4
3.3 Sudden affect…………………………………………………………………….5
3.4 imitative behavior…………………………………………………………….. 6
3.5 Ruin self Confidence…………………………………………………………..7
3.6 Stop all outside help…………………………………………………………..8
3.7 Mean deference…………………………………………………………… 9
3.8 it's always your fault………………………………………………………9
3.9 Panic of the breakup of the relationship…………………… 10,11
4 Spying story……………………………………………………………………12,13
5 GJ President’s Speak…………………………………………………….14 -18
5.1 Chain of Custody ……………………………………………………………13
After the divider bar click on the PDF icon to access the document.
| gj_boletin_english.pdf |
RSS Feed