 I understand you have a quiz today 3 o clock 5 1 or 2 ok and you are here to prepare essentially for that quiz is it yes sir good. So, while you guys are preparing for the quiz let me drop a bomb shell to you with some exam details they are now available on my website date is on the 22nd of February 2013. The exam is going to be conducted in two badges batch 1 and batch 2 I am going to be announcing the roll number shortly. The first batch is going to be having the exam from 10 am till 1 pm the second batch from 1 30 pm till 4 30 pm ok. So, these are the details so there will be 5 questions that I will be asking you to answer in 3 hours. So, long so far you have been doing 3 questions in 3 hours in the exam there will be 5 questions in 3 hours absolutely no sharing of information before or during the exam because remember the exam is going to be held in two badges and most importantly equipment ok. So, no sharing of drafters set squares pencils erasers I request you to bring only your mini drafter your drawing instruments set squares stencils pencils and eraser a piece of clock they can be brought in a file folder or a simple polkin bag like this ok. Keep everything except for your mini drafter inside and bring this along with you it is very important for you guys not to bring your bags and cell phones you will not be permitted to keep your bags and cell phones either outside or inside the hall for batch 1 I want everybody to be inside the drawing hall by 10 o clock shop ok. 10 1 things become difficult 10 2 things become more difficult 10 5 10 10 things become impossible do not do that 10 o clock sharp I want everybody inside for batch 2 likewise I want everybody inside the drawing hall by 130 p m capital S capital H capital A capital R capital P sharp ok. So, I might as well give you the questions so that you can go home prepare the sketches and come to the exam ok. So, here is question 1 no I was not serious things will become a little difficult in between 1 and 130 ok. So, we have a plan as they are my way page, but I just want to explain to you. So, students of pupils from batch 1 will be working in drawing hall 1 and 2 ok around 1 o clock they will come out they will follow the blue arrows ok. So, there is this corridor that you already know the end on the left leads to the faculty building the end on the right leads to the I M E building ok. So, you guys in batch 1 will step out and turn to your right and stay here for half an hour you will be quarantined codoned. Stay there for half an hour till pupils from batch 2 occupy their places in drawing hall by 130 you will be released batch 1 will be released batch 2 will be ready for the exam ok. These are the barricades and will make sure that there is no mass transfer momentum transfer energy transfer across these barricades physics 1 or 2 no transfer information. So, last time we did missing lines this time we are going to do missing views. So, those who are coming late make sure you do not do that on the 22nd of Feb just by 30 seconds or 1 minute the doors are going to be closed for the main drawing hall and we cannot do much ok. So, make sure you are on time or rather before time in this case. So, little basics the region in the red front view the region in the green top view the region in sky blue right inside view hinge lines if you have a point in one of the views what would it is image look like in the top view and the profile necessarily a line could be a point and could be a line. So, if the image of this point in one of the views is a line then if you project this thing in the third view you will get another line ok. So, these lines are going to be perpendicular to the respective hinge lines this true for all image planes or all views. For example, if you have a point in top view and if it is image is a vertical line in the front view if you take the images if you take the image in the profile views going to be vertical line ok. Likewise if you have a point in the profile view in this case the right inside view and if it is image in the frontal view is a horizontal line you take the respective projections and you will see that the image of that point in the top view is also going to be a horizontal line. So, pass a good if you have a slant line in the front view and if it is image in the top view is a horizontal line then what do you expect a vertical line Wunderbath. If the image of that line in red is another slant line in the top view what do you expect slant line. So, these are certain basics that you have to keep in mind if there is a line which is vertical in the top view and if it is image is also vertical in the front view what do you expect the image of these two lines what do you expect break the sound consider a point on the line the image of this point is this line figure out the corresponding image over there consider this point image of this point again would be a line figure out the corresponding image over there and do the other way round as well this point this image this point this image what do you get you would get a rectangle so this something which is important. So, both the possibilities so some of you are saying that this diagonal is also a possibility and this diagonal is also a possibility right do you agree good. So, what does that mean the solutions not unique the solutions not unique which makes things even more challenging when you are thinking about missing views I will come to that, but for now let us stick with the rectangle thing. So, the impression given information of a point or line in two views the projection in the third view should be possible may be unique may not be unique depending on the situation what should be possible right I will try to use this information to try to construct the missing view and alongside the three dimensional object just in case let us say if I extend this line by this little bit the image of this line is also this green line if I take the respective projections I will get another plane in the profile view. So, uniqueness is something that we will have to address while constructing the missing view as well as the solid. Let us take this first example two views are given the front view and the top view and when I say two views are given I mean that nothing is missing in the two views the entire information is given what is not given as third view and we have to draw that. So, while I am going to be drawing the third view I will also be drawing the three dimensional solid that the three views would represent. So, here we go look at this figure carefully you can think about this figure as being divided into a bunch of lines and points likewise you can think about dividing this figure into a bunch of lines as well. Let us focus on this line and this line. So, these two lines would represent what assuming that we are not thinking about the diagonal lines as of now that would represent the plane and that would represent the plane on the back side of the object. So, this is what the plane is right. So, if you are with me say yes if you are not with me raise your hand and feel free to ask a question how about this line and this line you will also get a plane. Now, what I have done is I have drawn the extended plane. So, I have assumed that this line extends up till this point over here just to get the solid in perspective I have drawn this plane. So, that the plane extends till this edge how about this vertical line here and this vertical line here I get this plane. And then this edge is something that I see in the top view from here to here this edge is something that I also see in the top view from here to here this bottom edge is the same thing I see this in the top view and also I see a part of this in the front view this vertical edge I see in the front view right top view right vertical right vertical edge front view the vertical edge on the right this is again the front view at this point you have some information as to how the solid might look like. Use your judgment and try to finish the solid this is how the solid might look like once you know how the solid looks looks like the front view you get the front view when you look at the object along this direction you get the top view when you look at the object from this direction and the right hand side view is from this direction you are ready if you are convinced that this object if you are convinced that the front view and the top view shown correspond to the object that you have drawn you are ready to draw the right hand side view use projections you would see this face you would see this face you would see this face and then you would see this face. Things can get tricky things can get tricky so you will have to be a little careful another way to think about this start with a 3 dimensional block start with a 3 dimensional block assume that is solid and depending on what your views depict start cutting different parts from that block that is the other way. So, assume that you have a clay box or a box made of wax start cutting different blocks different parts from that till you get your top view right your front view right ok once you are convinced then you are ready to draw the profile view of the third machine ok. So, it is it is experience essentially there is no method that is the right method ok. So, it is experience that is going to help you draw these objects example 2 the front view given the top view given ok use the fact that the image of two vertical lines and the two views will be a plane in the third view use that fact corresponding to this line and this line you will get a plane at the back right when you say. So, when you agree say yes when you agree say yes corresponding to this line how many lines you see here 2 is it yeah 1 2 how many planes you expect how many planes you expect. So, the image of this line is this guy over here the image of this line is also this guy over here and by the way this is also discretized into two vertical lines right. So, how many planes you expect for now let say they are going to be 4 planes this is the first plane that would correspond to this line here and this line here second plane corresponding to this line and this line the third one corresponding to this and this and the fourth one corresponding to this line and this line what would this plane correspond to isn't this how many planes do I expect here and here or these planes yes do I see this line in any of the views top view do I see this line do I see this line top front rather both do I see this line do I see this do I see this finish your object and now try to sketch or try to outline the object in three dimensions and your object will probably look like this yes simple is it simple good. So, once you have this object now you are ready to draw the missing view which would look something like this yes good so far so good let us think about loops loops a loop is what is a loop you know what that is let us think about loops how many loops are there in the front view how many loops are there in the front view well actually mathematically that three, but for now we will assume that these loops are not intersecting with each other on the one loop is not enclosing the other loop. So, this is the loop that you see in the top view this guy here this is the loop that you see again in the top view this is the loop the L loop that you see in the front view and then you see a rectangular loop again in the front view now the problem is just to place these loops appropriately in 3D how do you do that let us see. So, this is where the green loop is this is where the image of the green loop is. So, the green loop is here in the top view the image of this is at the top in the front view. So, this loop stays here the red loop this loop the image of this is over here in the front view. So, this loop what happened to it will go down the image of the sky blue loop in the front loop is at the bottom in the top view. This is your red loop what is the image of that in the front view this line here there is a difference in height between the green loop and the red loop. So, the green loop is staying at the top the red loop is going to be pushed down this is your sky blue loop the image of that is here in the top view. So, this sky loop will stay there this loop will stay there will get pushed along which direction. So, what you have done instead. So, these loops they represent different faces of a 3 dimensional object. So, what you have done is you have determined the placement the relative placement in 3 dimensions. Once you have done that all you need to do is draw the missing lines right simple again once you know the object you know the missing line. How about this how many loops do you see in the front view 2 1 of them is the 1 in the light brown. So, these are 2 loops that you see in the front view correspondingly in 3 dimensions they are where they are placed in the top view how many loops you see 1 2 3 4 fine you need to play with them you need to push them back and forth down and up this is where your red loop is it stays at the top your sky blue loop this one gets pushed down by this height the brown loop gets pushed for the down the purple loop stays where it is the light brown loop gets pushed along this direction. Once you have placed these loops appropriately fill out the rest of the lines the green loop the green loop comes down. Now, fill the rest of the lines complete the rest of lines once you know the object you know it is 3 dimensional you know it is third view given 2 views this is a little tricky and challenging with the loop method work here anyhow let us do conventional stuff this plane corresponds to which 2 lines this line here and this line here and this plane corresponds to this line this entire line and this line at the back. Likewise the plane here on the front corresponds to these 2 lines with me with me good. So, this is your plane of the front view this is your plane of the top view of course and this is your plane of the profile view in the front view you would possibly see a line here essentially this space here and then you would see some like this right this is a tricky part this is something that you will probably need to guess you will probably need to guess. If you look at the solid from here you will see this line you will see this line you will see this line and you will see this line, but if you look at the solid from the top you will see this triangular wedge taken out from the block corresponding to wedge you have this triangular feature here now how about these 2 triangles it is a plane it is a slanted plane are you sure no sir well if it is a set of planes if there are like 2 planes then there has to be a line of discontinuity between those planes. So, what you are saying is these 2 triangles will constitute 2 planes try it out try it out, but let me go with your option first a single plane a slanted plane. So, what are the vertices of that plane will be somewhere here the second vertex will be here and the third vertex will be here correspondingly the second vertex will be here the third vertex will be here now imagine that you are working with this imagine that you have drawn the solid. Now, try to verify if you get the projections in the front view and the top view right if you do the solid is ok was which line this line here. So, remember and remember this golden rule that if you are getting 2 planes or if you are getting a single plane with 4 points lying on the plane make sure that all 4 points are local planar otherwise you are not doing things right. Once you get the sense of how the object is going to look like in 3 dimensions work out the outlines once you know what the object looks like work out the third missing view. Let me tell you and let me warn you rather that this is not at all trivial for certain cases for certain cases straight forward, but for many other cases it is not trivial. So, you have to give your CPU a hard time let me let me, but would the corresponding line appear over here yeah absolutely you are most welcome yeah and then I have 2 planes one would be this one another would be this one how about the hidden lines then. How about the hidden lines I sure try it out try it out try it out. So, there could be multiple solutions. So, try it out and do verify if the loop method would work in this case another example. So, this time I will not speak I will let the screen speak ok. So, just follow and stop me wherever you have doubts do you agree are you with me good I will talk about these red lines later, but for now let me finish up the solid would those red lines be there, but on the money. Again coming up with the third view is not. So, difficult how about the loop method you see the first loop here trapezium second loop rectangle third loop at the top fourth loop again at the top and then you have this rectangular loop at the top and you have this triangular loop on the front or in the front the purple loop has to go where the red loop has to go where here the green loop stay there the brown loop would it stay like that or would it change in shape like. So, this sky blue loop stays there the black loop here make sure you have the solid and once you have the solid you have the profile view two problems before you go from here on the left are shown the front view and the top view of solid one on the right are shown the front view and the top view of solid two they are identical to each other. And at this time it does not matter if you are using a first angle scheme or the third angle scheme since they are identical to each other in both cases try to find how the respective solids will look like number one and once you do that try to find the missing profile view ok.