Chopper 5 Composite
An analysis of the live WNYW helicopter video of UA Flight 175 striking the World Trade Center
Abstract
Introduction
Premise
Objective
Methods
Measurement Accuracy
Frame Rate
Unit Conversions
Observations - Raw Video
Observations - Stabilized Video
Conclusions and Discussion
CGI vs. Video
Chroma Key
Hypothesis 1 - Old School
Hypothesis 2 - New School
About the Author
The WNYW "Chopper 5" video of UA flight 175 crashing into the World Trade Center which aired live on 9/11 must be a video composite. The moving plane image must have been recorded separately from the image of the twin towers.
Accoring to Newton's first law of motion, an approaching airliner flying through air will "keep on doing what it's doing". That is, the airplane is either travelling a constant speed, accelerating or decelerating. It cannot speed up and slow down repeatedly. Plotting velocity as a function of time, the approaching airplane must present a smooth line on the graph. Constant velocity would be a straight horizontal line.
The apparent velocity of a jetliner on video can be contaminated by various noise factors including atmospheric interference, video compression artifacts, and, most importantly, camera motion. Simply moving the camera while recording can cause any object to appear to speed up, slow down, stop, go backwards, etc. Being on a helicopter, and also being controlled by an operator, the chopper 5 camera is never still. Rather it moves around, mostly to the left, but also up, down, and to the right. The camera movements appear to be quite smooth, however.
The raw video depicts rapid increases and decreases in velocity of up to 186 mph (a jagged line on the graph), which is assumed to be caused by some combination of noise factors, especially including camera movement, because atmospheric disturbances and video compression artifacts do not appear sufficient to explain the magnitude of such deviations.
Besides the moving airplane, this video contains stationary reference objects, the twin towers. Stabilizing the video effectively removes camera movement from the raw clip. If the variations in apparent velocity were caused by the observed camera movement, stabilization could only have the effect of reducing the apparent fluctuations in airplane velocity (straightening out the jagged line). However, the opposite occurs. Stabilizing the video has the effect of amplifying and randomizing the apparent velocity changes. The line on the graph becomes even more jagged. Other noise factors are judged to be insignificant, so these data are explained by camera motion on the plane, camera motion not present on the twin towers, thus not removed during the stabilization process.
After a 0.3 second disappearance inside the tower, what appears to be the nose of the aircraft exits the building, apparently now coming from behind the tower. Although travelling much slower than the approaching airplane, this "nose cone" also appears to accelerate and decelerate repeatedly. The stabilization process again fails to smooth out the jagged velocity data, and introduces a noticeable spike at frame #41.
Frame #7 shows a very evident "pixel halo" around the nose of the aircraft, indicative of a "cut and paste". In fact, all of the frames show signs of cut and paste, as pixels surrounding the plane stick out against the sky.
If this is a legitimate video, these anomalies are not easily explained. However, they can be explained in terms of well-known video layering techniques. The simplest explanation for the data is that the airplane was recorded seperately from the towers, and had its background removed (sloppily on frame #7). This airplane recording had unstable camera motion which introduced the variations in velocity. The observed camera motion in the Chopper 5 twin towers video was negligable by comparison.
Introduction
The planes of 9/11 remain a hotly controversial topic within the 9/11 truth movement. Even among those who all readily agree that 9/11 was an inside job, some think real planes were used, while others assert that the plane crashes witnessed by millions on tv were "video fakery".
The "Chopper 5" video aired live on 9/11. It is the live shot which came the closest to actually showing the impact of the plane into the tower, although it did not. In actuality, all of the live "plane impact" videos showed the plane disappearing behind the tower.
After analyzing various videos, researchers such as Gerard Holmgren, Rosalee Grable (aka the Webfairy), StillDiggin, CB_Brooklyn, Killtown and Morgan Reynolds have concluded that Boeing passenger aircraft did not strike the twin towers as widely reported. This is based upon several mutually supporting lines of evidence and reasoning:
- In various videos, including the so-called "ghostplane" video, the Boeing 767 appears to penetrate the outer wall of the south tower effortlessly, without crashing, breaking, bending, twisting, or even slowing down. Frames taken during the penetration show no damage to the aircraft at all, nor to the wall of the building (see Grable).
- Two different videos appear to show flight 175 approaching from two decidedly different angles through 3D space. (see StillDiggin 2006)
- In several videos, a brief bright flash appears at the tip of the aircraft nose, just prior to entering the building.
- In the WNYW "Chopper 5" video, a wide angle shot fails to depict flight 175, at a time and place when flight 175 should be in the picture. (see StillDiggin 2006)
- In the "Chopper 5" video, which aired live, what appears to be the nose of the airplane exits out the opposite (north) side of the south tower, at about the 89h floor, followed by a quick fade down to a black picture.
- In at least one other video, which did not air live, a similar, silvery cone-shaped object appears to exit the north face of the building, at about the 89th floor, afterwards it is consumed by a flame. This flame is a distinctly yellower, lighter color than the other, more orange parts of the "fireball". (see StillDiggin 2006)
- In another video, which did not air live, smoke exits the north face of the building, at about the 89th floor, and does not look at all like the nosecone of an aircraft. (see StillDiggin 2006)
- In the Naudet brothers video, which is the only video to capture the north tower strike with any appreciable resolution, the object which strikes the tower does not appear to be the shape of a Boeing 767, and is not large enough to be a Boeing 767, and creates explosions in the pattern of an "N" rather than a straight line as would be expected. (see Grable)
- Both towers exhibit a nearly "plane shaped" hole punched clear through the outer walls. It is argued that passenger aircraft, which are mostly lightweight aluminum, could not and would not penetrate the dense grid of steel columns and reinforced concrete floors so completely. Instead, it is thought that on impact a passenger aircraft would break up, large parts would bounce off and fall to the ground. Recall that Newton's third law of motion states that for every force there is an equal and opposite force. Whatever force is felt by the wall, would also be felt by the much weaker aircraft (see CB_Brooklyn).
- Accepting the overall "inside job" hypothesis, powerful arguments have been advanced that the perpetrators would never risk using real planes (see Holmgren and Killtown).
Other researchers in the 9/11 truth movement have argued in favor of real planes. Steven Jones has opined that there is "hard evidence" to support real planes, and cites the "swaying of the tower", multiple videos, and eyewitnesses. Video engineer Eric Salter has authored a paper in support of real planes, published in Jones' Journal of 9/11 Studies. (see Salter 2006) This came after Salter's email debate on the subject with Gerard Holmgren (see Holmgren/Salter debates).
Premise
If real, flight 175 can be presumed to exhibit one of three velocity patterns as it approaches the tower:
- holding a constant velocity (most likely)
- accelerating
- decelerating
Given Newton's first law of motion, it is simply not possible for an aircraft flying through air to speed up and then slow down within the short (<1 seconds) time span of the approach. (see Wikipedia on Newton). There would be no real-world mechanism to explain such behavior. Speeding up and slowing down repeatedly would be thoroughly ridiculous.
Plotting velocity as a function of time, a constant speed would appear as a straight horizontal line on the graph. Acceleration would appear as an upward sloping line, deceleration as a downward sloping line.
I shall rely on the following two facts to propel this investigation:
- Any amount of camera motion at all is going to affect apparent velocity, by the exact amount, and in exactly the opposite direction as the camera movement.
- Any such video containing camera motion, and also depicting objects known to be stationary, may be stabilized, and then anaylzed as if it had been recorded with no camera motion.
Objective
My objective is to analyze and interpret the velocity of UA flight 175 on approach to WTC2, and the nose cone-shaped "debris" which exited WTC2, as recorded by "Chopper 5".
Methods
Obtain Chopper 5 video in 640 x 480, 30 fps format, import into Image Ready and Photoshop. Increase image size 200%. Derive plane outline using magic wand tool on suitable frame(s). Position plane outline around plane in each video frame, going for best overall fit. Record velocity readings as change in apparent position from previous frame. Save as two copies.
Stabilize video on copy two, shifting each frame until edges of twin towers match vertical red lines. Record velocity readings as above, this time for stabilized video. Crop videos to include flight path and tower.
Create graph, velocity as a function of time, plotting raw data as blue, stabilized data as red.
Make general observations, noting apparent hierarchy of video elements. Offer discussion and conclusions, based on observations, reasoning, and knowledge of video production techniques. Hypothesize. Include discussion of measurement accuracy, frame rate, and any other relevant issues.
Measurement Accuracy and Noise
The motion of a real plane travelling through air is smooth. Changes in velocity are gradual. Plotting velocity as a function of time, a real plane must present a smooth line on the graph. On video, any instability of the velocity must be attributed to "noise" of some sort.
The atmosphere can cause distortions in the apparent position of real objects, as light is reflected and refracted off of particulate matter in the air between subject and camera. This tends to cause wave-like ripples, apparently bending or stretching the subject. No such distortions are observed in the Chopper 5 video, the plane appears rigid. So this type of noise appears insignificant.
Converting video to digital can cause so-called "compression artifacts", as software attempts to reduce file size by making adjacent pixels the same color. This may cause errors when pixels are already simiar. In Chopper 5, the wing tips may reflect sunlight and become close to the color of the sky, and compression may make them the same color. Where contrast is sufficient, such as on the fuselage, tail, left engine, etc. compression would serve to make plane outline more distinct. Though it might erase wingtips, video compression would not tend to alter the overall size or position of the plane.
The most significant potential source of distorted velocity on any "hand held" camera shot is camera motion. Simply moving the camera around can cause the apparent velocity of any moving or stationary object to go crazy.
Frame Rate
The present study assumes a constant frame rate. If the Chopper 5 video was not recorded with a constant frame rate, or if there are frames missing from the original recording, this entire paper may be dismissed. Specs for standard broadcast video in the U.S. are given by the NTSC (National Television Standards Committee). A video frame is 480 scan lines tall, and is captured in two passes of 240 scan lines each, first the "odd numbered" scan lines, then the "even numbered" scan lines. Each of these passes is known as a "field". One odd numbered field is combined ("interlaced") with one even numbered field to make one video frame. These interlaced frames are recorded and played at a rate of 30 frames per second. (Actually, 29.97 frames per second, but often referred to simply as 30).
Digital video can be played back at any frame rate. Conversion from NTSC standard to digital with a frame rate other than 30 fps will cause loss of some frames. Conversion to a frame rate of 20 per second, for instance, would involve discarding one out of every three frames.
The copy of the the Chopper 5 video used for this analysis is NTSC standard 640 x 480 pixels, and 30 fps. There is no reason to suspect that any frames are missing, nor that the frame rate of the original recording was anything but stable.
Unit Conversions
Width of tower = 182 px = 208 feet
Scale = 1.14 feet/pixel
Distance from edge of picture to tower = 392 px = 446 feet
Nose travels from edge of picture to tower in 17 frames = 17/30 of a second
446 feet in 17/30 second = 788 feet / second = 537 mph
Largest variation in apparent velocity = 8 px/frame = 274 ft/sec. = 186 mph
Typical variation in apparent velocity = 5 px/frame = 182 ft/sec = 124 mph
On first viewing, the video appears to be a typical news helicopter shot, albeit of an extraordinary news event. It originates from WNYW in New York, and is being fed to a local Channel 11 station on the west coast. It appears to be a live helicopter shot of the twin towers, with graphics overlays of the WNYW logo, Channel 11 logo, time, temperature, etc. Studying the Chopper 5 video reveals several curious observations.
The helicopter is over New Jersey, about 4 miles west of the twin towers. Although the twin towers are the news story of the century, evidently the pilot is happy with his location, as the helicopter does not appear to be heading toward the towers at all. The video begins with a wide angle shot, then zooms in, almost all the way. After holding this zoom setting for a moment, the camera operator then zooms the rest of the way in. Within 3 frames of this final zoom, flight 175 enters the picture from the right side. This is quite a coincidence in timing. The actual plane impact is not visible, as the south (impact) face of the tower is angled slightly away from the camera. The plane disappears into the building with no apparent damage to itself or the tower, then appears to begin exiting from behind the tower on the opposite side. The video feed (but not the graphic overlay) fades to black very quickly after this.
On one particular frame, frame #7 in my study, the airplane appears to show clear signs of having been pasted. Notice the "pixel halo" around the nose.
Here is the same frame with brightness and contrast adjusted, and the pixel halo becomes even more obvious. In fact, it appears that a portion of the fuselage, under the tip of the nose, was erased. Also notice that the air behind the wings is considerably more pink than the background.
On approach, the plane appears to speed up and slow down repeatedly before hitting the tower. We know that the plane cannot speed up and slow down so quickly in reality, according to Newton's first law. However, the apparent changes in velocity could be explained by camera motion. In the Chopper 5 video, the plane travels from right to left, but during this time, the camera angle also pans from right to left, mostly, with a somewhat random action. This would have the effect of reducing the apparent velocity of the airplane, in a somewhat random fashion. Fortunately, the video contains fixed objects, the twin towers, so it is possible to stabilize the video, and then analyze it as if there had been no camera movement to contaminate the motion of the plane.
Observations - Stabilized Video
Stabilizing the video amplified the instability of the airplane velocity.
The plane appears to speed up and slow down repeatedly. It varies from a maximum of 27 pixels/frame (629 mph) down to a minimum of 19 pixels/frame (443 mph). Upon hitting the tower, the plane appears to slow down drastically. Then, during the entry into the building, it appears to speed up just as drastically.
Following entry the plane disappears inside the tower. The disappearance lasts for 9 frames (.3 sec), after which what appears to be the nose of the airplane begins to exit the opposite side of the building, coming from behind the building. This event has become known as "Pinocchio's Nose".
Pinocchio's nose also appears to slow down and speed up. An initial velocity of 10 pixels/frame (233 mph) is measured, after which the nose decelerates down to 4 pixels/frame (93 mph). Then, it appears to accelerate back up to 8 pixels/frame (186 mph), decelerate again, and accelerate again.
There are two fade-out frames, the first being about 10% faded down, the second about 50% faded down to black. The second fade frame depicts the airplane nose-cone and an explosion flame. This flame appears in front of the airplane nose-cone. The fade-out frames are followed by many frames (about 1 second) of complete black. When the video fades back up to picture, no trace of the plane remains.
Conclusions and Discussion
The chopper 5 video is a composite. The video of the plane must have been shot separately from the video of the twin towers. In both the raw and stabilized versions, the plane appears to accelerate and decelerate, repeatedly. This is an impossible feat in reality, and is most easily explained as camera motion affecting the apparent velocity of the plane. This camera motion is present on the plane, and is amplified on the stabilized video which holds the towers motionless.
On a legitimate video, stabilizing the video frames could only serve to stabilize the motion of the plane, straightening out the jagged graph line, at least somewhat. The fact that the opposite occurs is proof that the apparent motion of the plane was influenced by camera movement, camera movement not present on the twin towers. The camera motion on the twin towers was insignificant by comparison.
In a real crash, a plane could not possibly accelerate while entering the tower. Yet in this video, the plane appears to do just that.
"Official" sources state that what appears to be the exiting nose of the airplane is actually "debris". How the debris would form itself into a size and shape indistinguishable from the airplane nose is not clear. In any event, whether debris or airplane nose cone, it appears to slow down, then speed up, slow down, and speed up again. Other than camera motion, there is no explanation for this behavior. Again, this must be camera motion separate from whatever motion was present in shooting the twin towers, as this motion has been removed from the video.
Frame #7 reveals tell-tale signs of having been "cut-and-pasted". The area around the nose of the aircraft is a different color than the sky, more pink, and pixels under the nose appear to have been erased in what looks to me like the swipe of a digital paintbrush. Perhaps this was an inadvertant mistake, perhaps it was a deliberate clue.
All the other frames have the same kinds of problems. I would venture to say that the plane was recorded on a day when the sky was considerably more pink than it was on 9/11. This subject warrants a study of its own.
Due to the camera motion, the realistic blending of the airplane into the sky, and the sloppy photoshopping (particularly on frame #7), I do not believe this is a computer generated airplane, as others have suggested. Rather, I think it is real video of a real 767. I believe the masterminds of 9/11 chose crystal clear days to carry out their deeds for very important reasons: it is the easiest type of atmospheric condition to repeat, and the easiest on which to remove sky from video. (They may have required a crystal clear day on 9/11 for other reasons as well, see Judy Wood). I suspect that a real 767 was videotaped flying north and banking to the left, then leveling out, on a similar crystal clear day, at around 9 a.m.
On the video which eventually became the overlay for the chopper 5 video, the plane entered the frame from the right, at around 24 pixels/frame. Camera unsteadiness caused the apparent velocity to fluctuate. The camera began tracking the plane, reducing the apparent velocity down to around 10 pixels/frame, as the plane began to level out. It is this phase that eventually became Pinocchio's Nose.
Multiple videos were made from multiple cameras by multiple camera operators, capturing the flight from a great number of different angles and distances, including helicopter shots from above. The backgrounds from these videos were removed, leaving just a plane flying against a transparency. These multiple videos became overlays for the many "amateur" videos which emerged later.
Locations were then scouted around the twin towers, locations with a view of the towers, which most closely approximated the viewing angles of the 767 flight already recorded. Overlaying the prepared flying plane images onto another video source (live or recorded) is easy, as the background has already been removed.
It is also possible to remove a particular color from a video source in real time, and make that color become transparent. The technique is known as "chroma key", and has been standard TV studio trickery since the 1960's. One color (usually green or blue, but could theoretically be any color) is chosen as the "key". Two separate video images, A and B, are combined together, with A on top, and B underneath. Any area in video A which is the key color becomes transparent, revealing video B underneath. Everyone has seen chroma key overlay when the TV weathercaster appears to stand in front of a giant satellite map. In reality, she is standing in front of a well-lit green wall, and the satellite map is combined with the live camera shot in the control room.
How Did They Create the Chopper 5 Shot?
In creating the illusion of a plane entering a tower, 3 video layers are required (not counting all the TV station logo graphics, which I ignore). The airplane needs to appear on top of the live video, then the world trade center tower needs to appear on top of that. This could have been done one of two ways, "old school" or "new school".
The airplane video on transparency "Layer B" is pre-recorded and waiting to go. Live video of the towers is split into two copies, "Layer A" and "Layer C". The sky color is selected as the key color, and Layer A is chroma keyed to remove the sky in real time. The three layers are combined, C on the bottom, B in the middle, and A on top. Thus the airplane is on top of the sky, yet underneath the twin tower.
A careful examination of the the exiting nose cone provides further evidence that this is a composite video, and does not depict an actual real life event. The west wall of the tower is facing us, and the tower is angled so that we can just see a bit of the north wall (to the left). The south wall (to the right) is angled slightly away from us. If the nose cone (or debris, or anything) exited the north (left) wall of the building, in passing it would eclipse our view of the northeast corner. This does not happen. Instead, the nose cone appears to slip out from behind the building, as we continue to see the northeast corner until the explosion flame comes out.
As the nose cone exits the building, the explosion flame appears in front of the exiting nose cone. This requires the software to identify the flame as "keep". That is, the flame must not be too close to the same color as the sky, otherwise the software would remove the flame from layer A, and it would appear behind the nose cone. The fade frame is instructive, clearly showing the the flame as being much more yellow than the sky. Chroma key would have had no problem keeping the flame while continuing to remove the sky from Layer A.
Hypothesis 2 - New School
As with hypothesis 1, the flying plane is pre-recorded, with background removed.
Computer software was used to model the twin tower, and mask it off dynamically in real time. The program uses "find edges" to identify the location of the tower in the picture. Again, the crystal clear weather on 9/11 is important, as there were high-contrast boundaries defining the shape of the towers. This, and the fact that the towers were essentially rectangular solids, makes for an easy shape to model.
This is similar technology to the "First and Ten" system by Sportvision that paints a virtual first down stripe on the football field. First introduced in 1998, the software contains a model of the field, is able to "key" on the color of the turf, "painting" the stripe only on the turf and not on the players. Most innovative, the system is able to follow the tilting, panning, and zooming of the camera, and to resize and move the first down stripe accordingly, in real time (see Sportvision site).
This technique would eliminate the need to chroma key the sky. Rather, it would model the location of the world trade center tower, and erase pixels in real time from the plane layer at all points corresponding to where the tower is.
However, it is not possible to know the shape of the explosion ahead of time. So, it would still require chroma key to identify the explosion, and erase the airplane accordingly, making the airplane appear behind the explosion. If this new school technique were used, it would have been easier to simply mask off the entire picture to the left of WTC2. This would have prevented the nose cone from ever appearing to exit the building. Yet, the nose cone does come out, apparently from behind the tower, just as it would if it were on a seperate video layer from the tower. For this reason, I prefer the "old school" hypothesis as having the greater explanatory power.
About the Author
I am a music composer and producer by profession. In working in film and television, I've gathered extensive experience with digital video. This includes analyzing video frame by frame, working with different time-code bases and different frame rates, and computer generated special effects. I've also produced two music videos which employed chroma key "green screen" technique. I am familiar with its possibilities and limitations.
In my opinion, based on other studies by other authors, the evidence and scientific reasoning support the idea that no planes crashed at any of the 4 "crash locations" on 9/11. In our view, those who argue in favor of real planes mostly ignore, rather than refute, our scientific argument against planes.
