Arjun Main Battle Tank (MBT)

[Shaitan]

mark 1 and 2 animation

 

[ersakthivel]

read my post again until you understand it, before you make another reply.

you read my previous post detailing with the techniques of perspective drawing again.And get some god books on perspective drawing and read more about the purpose of projection of planes .

 

[ersakthivel]

Now that I see ersakthivel liked you post. I have to ask what you really mean here. Because you liked my original post, and the part you quoted doesn't deal with any estimation I made, it deals with skj and ersakhivel. Did you mean to say that because skj and ersakhivel claim to be engineers they should know better or is it a general complaint to all measurements done on photos?
STGN

measurement on photos must be of the objects that are at equal distance from the observer and on the same plane to pass any validity test.
using the same pixel measurement for an object in front on a plane near the observer and another which is at a very large distance from the observer is patently wrong and misleading .

Any more pixel based estimation dealing with two different planes which are at two different distances away from the observer is a waste of time.
So it is obvious that some people here are trying to introduce sterile acrimonious discussion once again in place of objective rational measurement based perspective technique,
Also people saying arjun turret is 2.5 meters or 2.84 meters in width are basing their arguments on the perspective distorted pixel measurement than the valid principles based on projection of planes.

 

[Tronic]

different tools for different purposes. we're trying to estimate lengths, not design cars for serial production.
the method isn't rocket science, you take a known length, say the width of the arjun tank, draw a line between the extremes of those 2 points, rotate the line until it's horizontal(or vertical),
measure the length of the line in pixels, then do a unit conversion from pixels to cm. then you take another length, and multiply or divide by the pixel conversion number,
to arrive at an estimate.
So if you have a known length that is 18cm, and that length on the image is 360 pixels, you do:
18/360 = 0.05.
then to find a similar length, you find another length on the same plane and multiply with 0.05.
accuracy of the measures is dependent on the number of pixels in the image, and the amount of perspective distortion present on the measured plane.

I know what you are trying to do, and that is fine. What you are doing is among yourselves, and while I understand, I'm not in agreement, nor confident of your measurements. My main issue is people arguing on the basis of engineers. This not what they teach design engineers, nor the way they expect them to guesstimate.

Now that I see ersakthivel liked you post. I have to ask what you really mean here. Because you liked my original post, and the part you quoted doesn't deal with any estimation I made, it deals with skj and ersakhivel. Did you mean to say that because skj and ersakhivel claim to be engineers they should know better or is it a general complaint to all measurements done on photos?
STGN

It was a general complaint against dragging in design engineers into this. I don't have anything against you guys guesstimating dimensions; I just cringed when I saw engineers being mentioned, as if this is something engineers do. We do not! In engineering design, it would be considered sacrilege to do something like this, and as I mentioned before, the person would be shown the door.

I'm not here to judge what you guys are doing is right or wrong (I just am not confident in your method); just saying that this is not something engineers would be banking on, so it is incorrect to be mentioning engineering design credentials here and giving the impression that this is how engineers work out dimensions.

 

[ersakthivel]

Okay , Let me simply clear the misunderstanding regarding the pixel measurements on objects situated at two different distances,

Take a pair of shoes,
Place one shoe on the front bonnet of the car,
Place another shoe on the top of the car, above the driver seat, two meters behind the first one,

Click a picture with a camera near the first shoe on the bonnet , and the second shoe on the top of the car in the frame.
now the shoe in the front appears atleast twice as big as the shoe on the driver sheet, if you measure both of them using pixel measurements ,
Does that mean the shoe on the front is twice bigger than the shoe on the back,
A big NO.
it appears so because the plane at which the first shoe on the bonnet is located is 2 meters in front of the plane on which the second shoe is located,
that's what I was explaining,

 

[opesys]

Okay , Let me simply clear the misunderstanding regarding the pixel measurements on objects situated at two different distances,

Take a pair of shoes,
Place one shoe on the front bonnet of the car,
Place another shoe on the top of the car, above the driver seat, two meters behind the first one,

Click a picture with a camera near the first shoe on the bonnet , and the second shoe on the top of the car in the frame.
now the shoe in the front appears atleast twice as big as the shoe on the driver sheet, if you measure both of them using pixel measurements ,
Does that mean the shoe on the front is twice bigger than the shoe on the back,
A big NO.
it appears so because the plane at which the first shoe on the bonnet is located is 2 meters in front of the plane on which the second shoe is located,
that's what I was explaining,

Why don't you actually take a picture of a large object or of some vehicle and upload and ask DejaWolf to measure it based on pixels only and verify the calculations...

 

[ersakthivel]

Why don't you actually take a picture of a large object or of some vehicle and upload and ask DejaWolf to measure it based on pixels only and verify the calculations...

See the size of the main gun barrel hole and the size of the head of the man on the turret, they appear to be same if you take direct pixel measurement ,
But we all know the main gun bore is just 120 mm and the man's head should measure significantly more than that(in fact close to double),

That is the error when you try pixel measurements of two objects located at two different planes that are at two different distances from the observer in perspective drawing.

 

[arkem8]

Mk-2 Arjun MBT

 

[arkem8]

Mk-3 FMBT Concept/Artists Impression

 

[ashicjose]

Manorama Online | Malayalam News | Kerala |

According to this news ARJUN MK-2 got the extra weight due to the low grade steel, the DRDO were actually trying to reduce the weight of the tank in mk-2 and some people in the defense ministry sabotaged it to favor the t-90.:shocked:

 

[Abhi9]

Some info about antitank rounds

 

[Dejawolf]

Okay , Let me simply clear the misunderstanding regarding the pixel measurements on objects situated at two different distances,

Take a pair of shoes,
Place one shoe on the front bonnet of the car,
Place another shoe on the top of the car, above the driver seat, two meters behind the first one,

here's another experiment: stand in front of your car so you cannot see the sides, at about 5-6 meters, and take a picture.
import the picture into photoshop, measure the width of the left headlight in pixels. now measure the right one, and compare the difference. it shouldn't be more than 10% or so. the less the difference is, the less the side-to side perspective distortion is.

 

[Dejawolf]

turret width measurement process:

1. measuring the width of the skirts in pixels, we see the widths are nearly the same. this way, we know the perspective distortion is very small, and width measurements
are therefore going to be fairly accurate.
2. on the real vehicle, all of these red lines are parallell.
3. we use these lines to determine where on the first picture the front turret edge is. we can see from this picture, its somewhere inbetween the yellow and blue lines.
4. here you can see the measurement points for the maximum and minimum turret width.
5. doing some calculations.
-first we find the ratio between the width over the tracks, and widths at the estimated positions of the turret.
-the arjun is 3.5m over the tracks. the 956 pixel red line represents this width we divide to figure out the pixel conversion ratio.
-we subtract the turret width in pixels, from the hull width at the blue and yellow lines
-we multiply the width with the estimated perspective distortion.
-we multiply the perspective-distortion adjusted width, with the pixel/cm conversion number.
-we subtract the difference from the hull width over the tracks, to arrive at our final value.

conclusion: Arjun turret is a maximum of 2.84m wide, and an (unlikely)minimum of 2.711m wide.

 

[Austin]

I think the 500 mm RHA @ 2km is for 125 mm Mk2 rounds , this should be comparable to the rounds that we use for T-90 i.e 3BM42

 

[Decklander]

Mk-3 FMBT Concept/Artists Impression

If you guys may recollect I had stated long back that Mk3 will have three men crew and separate crew compartment and maybe a turretless main gun.

 

[ashicjose]

Mumbai-based businesswoman appears before CBI in Kochi - The Times of India
Mumbai-based businesswoman appears before CBI in Kochi

KOCHI: Mumbai-based Subi Malli on Tuesday presented herself before the CBI unit here in connection with a probe into the alleged fraudulent deals for the supply of Arjun battle tank components.

It has been alleged that Malli, a businesswoman, had mediated in the deals. CBI officers said she arrived at their office in the morning for a daylong questioning.

"She is cooperating with the probe and the questioning will continue on Wednesday. She will be arrested only if the situation warrants," CBI sources said.

Earlier, the CBI had issued an ultimatum for her to turn up at the Kochi office. The premier investigation agency had also said Malli would be arrested if she kept on ignoring the summons.

Malli had presented herself before the CBI officials in Mumbai following media reports of her alleged role in defence deals.

It has been reported that Malli had in the last quarter of 2011 won tenders favoring Steel & Industrial Forgings Limited (SIFL) and Mysore-based AMW-MGM from the Indian Ordinance Factory at Medak in Andhra Pradesh and Heavy Vehicles Factory at Avadi in Tamil Nadu for the supply of road wheel arms and flanches for the tanks.

CBI had also unearthed the role of M Shanavaz, the managing director of SIFL and Valsan, senior manager of SIFL, in the deal.

The interrogation will help the CBI to ascertain the role of defence officials who have recieved kickbacks in the deal. The CBI had already confirmed the involvement of several defence officers in the deal.

 

[ashicjose]

KOCHI: Mumbai-based businesswoman who allegedly mediated in defence deals reportedly told the CBI on Thursday that she had received Rs 18 lakh as commission.
Subi Malli got Rs 18L as commission from defence deals - The Times of India

Subi Malli got Rs 18L as commission from defence deals

The commission, Subi Malli said, was shared with M Shanavas, former managing director and A Valsan, senior manager of the Steel and Industrial Forgings Ltd, CBI sources said. The alleged fraudulent deals were for supplying components for Arjun battle tanks.

"We have not arrested her since she is cooperating with the probe. We have allowed her to go after questioning her for the last three days. She has agreed to appear before us if needed," the sources said.

The CBI also interrogated Shanavas and Valsan in connection with the deals. "She has revealed the names of certain defence officials, who have received kickbacks for clearing the deal. We will question the officials after verifying certain details, the sources added.

It was in the last quarter of 2011 that Malli managed to get new tenders in favour of the SIFL and Mysore-based AMW-MGM from Indian Ordinance Factory at Medak in Andhra Pradesh and Heavy Vehicles Factory at Avadi in Tamil Nadu for supplying road-wheel arms and flanches for the battle tanks.

She allegedly played the agent's role in getting defence contracts in favour of the vendors after colluding with officials of Indian Ordinance Factories Service. The woman is the owner of a firm called Subhishi Impex in Mumbai.

CBI officials said the Indian Ordinance Factory had awarded tender for supply of road-wheel arms at a rate of Rs 8,500 a piece to SIFL and Rs 7,000 a piece to AMW-MGM. However, Malli allegedly used her influence to cancel the tender to float a fresh one quoting a rate of Rs 13,500 a piece to SIFL and Rs 14,000 to AMW-MGM.

 

[STGN]

measurement on photos must be of the objects that are at equal distance from the observer and on the same plane to pass any validity test.
using the same pixel measurement for an object in front on a plane near the observer and another which is at a very large distance from the observer is patently wrong and misleading .

Any more pixel based estimation dealing with two different planes which are at two different distances away from the observer is a waste of time.
So it is obvious that some people here are trying to introduce sterile acrimonious discussion once again in place of objective rational measurement based perspective technique,
Also people saying arjun turret is 2.5 meters or 2.84 meters in width are basing their arguments on the perspective distorted pixel measurement than the valid principles based on projection of planes.

What you say first is correct
But what you seemingly can't see, both the "blue" and the "red" plane are at roughly the same distance to the camera they are for all practical purposes the on the same plane.(look at where the vertical lines are placed on the hull, you have to take into consideration the height difference between hull side and skirt side.) as skj showed with his rough shadow based 10:12 which is close to my 10:12.5 .
So the conspiracy you are trying to concoct doesn't exist.
And who has said turret is ~2.5m wide?
STGN

 

[STGN]

I know what you are trying to do, and that is fine. What you are doing is among yourselves, and while I understand, I'm not in agreement, nor confident of your measurements. My main issue is people arguing on the basis of engineers. This not what they teach design engineers, nor the way they expect them to guesstimate.




It was a general complaint against dragging in design engineers into this. I don't have anything against you guys guesstimating dimensions; I just cringed when I saw engineers being mentioned, as if this is something engineers do. We do not! In engineering design, it would be considered sacrilege to do something like this, and as I mentioned before, the person would be shown the door.

I'm not here to judge what you guys are doing is right or wrong (I just am not confident in your method); just saying that this is not something engineers would be banking on, so it is incorrect to be mentioning engineering design credentials here and giving the impression that this is how engineers work out dimensions.

Can you tell how you would go about estimating/guestimating scale of pictures?
STGN

 

[Dejawolf]

Why don't you actually take a picture of a large object or of some vehicle and upload and ask DejaWolf to measure it based on pixels only and verify the calculations...

because it'll prove him wrong.

i did a backyard experiment myself:

32/32.95 = 0.97 = 3% error
35/36.59 = 0.95 = 5% error.

if you make sure to take the picture head-on, i think it's safe to assume an error of about 5-10%