Mtg 12/25: Wed-18-Oct-2023

Outline for Today

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Audio Transcript

• If that was the case so I'm sorry I'm not I'm not punctual today either. Because my car was calling to me. So here's my new computer
• let's see if I have all the parts here.
• Here's the old one.
• Just want to say
• thank you
• this
• training
• so I just want to talk about Well, first of all, let me say it's happy. Academic Integrity. X day of action.
• You concerned. So there's a presentation layer today about using generative AI and its relationship to academic integrity and so I'm quite interested to see that
• so I didn't so the marker and I had a discussion yesterday and would have been better to have discussion earlier. But based on some of the work submitted, we came up with a few more
• so I'm going to revise rubrics for the next assignments based on some of the things we found here
• which isn't so did you find that it was the instructions were clear? So what were the instructions
• GL programs
• So something I could have made more clear, it's about using the sample code but acknowledging it and describing what's.
• What you've added to it
• Okay, so I should have also included tomorrow about.
• More about the submission format. Anything else that was?
• Missing from.
• Anything else that could be added to make it more clear
• so instead of
• so instead of just making it six marks or implementation and two for comments, I'll break I'll break down future one so I'll give you some examples.
• So how do we indicate this a WebGL program
• let's where do we specify WebGL?
• Yes, required three Jas to code and then see making Okay, that's using three js it's not using them to function like to we can watch so let's get context. Right.
• JavaScript prefer single quotes
• Okay, so that's because we don't just be with a canvas we can have different contexts. Could have a 2d We can. We can have a number of different ones. So we wanted WebGL to context
• Okay, anyway, don't be too late. But the point
• so now we're dealing with viewing. There's two parts, right? We're establishing the viewing coordinates where we're looking, we're where we are the camera and where we're looking at and the orientation so how do we specify that
• looking from the eye point? So that's one point. So that that says where the camera is going to be now what other things can we can we use to indicate our position uniquely?
• So what other information do we need? If I have my camera here okay, my camera, we've established the opposition but I can I can look anywhere from here. So I'm not changing the camera, the eye position.
• Whatever of these information can I use to indicate precisely what where I should be looking? With a camera
• in this scene and the points that it's for,
• option. So we talked about three. So we're going to have
• like, I'm talking about perspective.
• Now. I'm just talking about where I'm going establishing the viewing coordinates. So I'm I'm here with a camera. Where should I be looking at Bob's?
• Yeah, so I have a position I need a point that I'm looking at XYZ coordinate for Yeah, x y and Zed for good.
• Right so we talked about this yesterday, last day. Right? So then all right.
• So now if I have my camera position, and I'm looking at let's say I'm looking at two projectors, so that's what was it
• Okay, so if I'm looking here with a camera so I have the camera position, I'm looking at something. What degree of freedom is Yeah, so I need to specify what is the up vector
• so when we changed so we had the hat
• and we make this CF factor. Then we see
• see that picture as we expect what happened when we made the up vector? Like this? What happens to the picture? Or what happened to the picture? If you remember from Monday
• Yeah. So it rotates so that this vector is pointing up. So the picture we see then is.
• I shouldn't
• so it makes sense. Okay. So if we have two vectors here, if we have the vector here between apps and the eye point, and then the app vector how do we make a third vector so we have coordinates basis for our coordinate system?
• So what what are the vectors do we want?
• Well
• so we can have
• a vector that's normal to the other two, and it's perpendicular to the other two is a cross from a cross product right.
• So then if we take this, make a trans transformation from our X, Y and Zed coordinates to these UV and n coordinates
• and we can think about looking down set axis here.
• We got a matrix transformation to so the neat thing about computer graphics is that so we have corn system that we're modeling things. We have a corn system we're reviewing things and then we can trance and can transform between the neural cell matrix multiplication
• so we talked earlier about clipping coordinates right. So that I guess what's, what makes it into the onto the screen into the viewport? Is is divine minus one one minus one to one.
• Imagine that mind straight this is minus one one.
• So, if we if we just if we don't do anything differently we can just see what will just look straight on to this?
• So, that's my default stats rejection they have so it's just learing Zed values. So that's why we do the Zed Zed test the depth then we're going to only draw the things that are closer than things out there things have been drawn.
• Thinking about our synthetic camera, how do we where we have perspective, usually
• so we have the camera.
• Then we have
• far
• so you can see this being transformed to minus one and one
• if we have a which which court system is that? Where is it? Where's it distances increasing as we go away? Into the screen
• so left hand is x times y it goes away if someone's pointing in the direction of positive Zed.
• So you can relate that back to this clipping volume. Now other thing so if we put the front and back of the clipping volume alignment with the front and back of our projection here we've got one thing taken care of right but what about the other things? So
• what's going to happen in a perspective projection so if we have somebody has the size looks like a letter chi with legs and arms. Anyway let's do it. Again.
• So they're about the same size. perspective projection. Is this one is this character going to be projected any larger than the image what about this character
• so what needs to happen is
• that was not right
• so this guy is still mad big. But then here we
• go that's not not the scale but the idea is items in the foreground are made larger because we're stretching
• to transform this into normalized coordinates the minus one to plus one coordinates. We need to stretch the front need to stretch the whole thing so these aren't this becomes a parallelogram or parallel a pipe it is that makes sense? Okay
• so we can specify the field of view and the y direction that's this angle.
• seem okay. In terms of a general idea of what's going on okay
• so we won't go any further than this this would be the last bit of material for the exam. And what do you think about exam questions?
• Found a supercharged turbocharged car. I would have a place like this
• maybe it would be maybe Cypress Hills I guess that's the highest elevation in Saskatchewan in the southeast corner
• that was insane because there's no connection.
• Evening was quite a concern
• I know it sounds up here
• so I try to link again it says 404 not found. So maybe it's
• there No, it was like totally fine. Like I
• didn't even give you an oh yeah. Well, that brings me joy.
• No, it was totally fine.
• Dr. Pepper. They talked about him in marketing. He was like they said, Dr. Pepper Dyer. I love that. Okay, where are you guys? I don't know how it works. For me I don't.
• Know isn't
• just an issue
• I don't
• know I'm not sure what happened.
• Just sitting for
• so long.
• Okay, I know what happened. I'm just like, these two laptops which I was forced to switch between every day aren't in sync.
• You Okay? I will get that fixed up right after class
• but for now, let's look at
• it wouldn't have been a problem. Except I fixed an issue that I was cleaning up the files each time I was refreshing the site. So if I had the old version of my script, it would have kept once it got up there and stayed there. But now I'm cleaning up so when it's not doesn't appear again. It gets removed anyway
• anyone see this yet? I apologize. I wasn't trying to play a cruel trick on you
• anyone know the peanuts cartoons? wasn't trying to be Lucy with like the football for Charlie Brown. Because what she does is she says I promise I'm gonna hold a phrase and kick the ball. And he's graduate be against his better judgment. believes her and then she pulls the football away. So he falls on his rear. He doesn't that happens many times. Anyways, that wasn't my intent
• Okay, so what is a pixel? So that seemed like a good question.
• Anyone like that as a question? Any variations on the question? That you would prefer?
• Okay, so how would anyone at how would you answer that question was the pixel smallest addressable community?
• Have a sample phenomenon to be represented or reconstructive Do you like that no first?
• Know it's really it's resolving and get extra marks for us
• extra five not
• so question is a pixel have geometry.
• Square and he told me that it isn't three times.
• It's not necessarily a square. That's right. But if we preserve the aspect ratio
• thing we're trying to reconstruct then then they're equal distance so most often associated with squares, I think. They don't have geometry in themselves because of their samples even though that's that's not a happy face answer.
• Okay
• we start from black describer sketch how to get the color weight using three parents of colors. When starting from wait and go to black.
• So what do we do to get from black to white? Do we add RGB so it's added?
• 1515
• the accumulation of the answer to it. Describe prism
• prism.
• will find you a plus one with a past
• cube
• I should just draw a bigger one light side just a Magento game so if we start here with black one direction we can add red we can add blue. Another direction you can add green
• so, blue and green is cyan. Blue and red is magenta and then red and green is yellow
• MS is white so, and then if we look at we looked down axis between white and black and we get a shape like
• this look looking at right from the side and you see something like this
• well usually we squish it into a corner like this. So round the circle is the hue and distance from the center to the edge is the saturation
• this is the value. So black here and what is the center of it
• so what happens if you want to go from white to black?
• So it's so this is a display. Laser additive started from black
• for printing on white paper, so if we print cyan, magenta and then we're subtracting colors from the spec,
• the light that's reflected from them. So is yellow and black as well. Usually because it's easier to get a nice black color if we start with black ink instead of mixing cyan, magenta and yellow
• which can be sometimes very muddy and also paver gets very wet because he applied three times
• does that make sense? Okay it's not a good question. If we say yes for you removed
• so for the answer, just these things that you said you wrote actually and the q will be in our control the cube to describe it. describe our scale
• test obviously is
• going to prevent drawing. You can draw on here or you can draw in here as well to see you should be able to do the horizontal lines straight absolute joke.
• Use that to make the cube
• so is that a fair question? Because we've talked about colors. Right. I could also ask what what does Alpha do? That's a great way.
• Evening Okay, so what about the concepts continuous and discrete? Sampling and quantization the thoughts about those
• so resampling I continuous phenomenon
• and then we get back from our sampling. We got a discrete representation so if we sample
• Yes
• yes. Find that religious organization
• Okay, so now it's time to allow us to reconstruct continuous a continuous phenomenon that we're trying to represent. Okay, does that make sense? So what about because I wrote my writing degree was
• in discrete come together to form sampling. Is that a correct assessment?
• We sample a continuous phenomenon. And that gives us a discrete representation of it. So what is what are enough samples? One day
• sir so let's think about the audio CD format
• so
• I do a CD format samples at 44.1 kilohertz. So what what's the highest frequency we can reconstruct? No, we did this
• that's the highest frequency
• so a few different thinking about an image.
• Say we have this shape for some reason?
• Got let's say they got to. But if we take
• so here think of having a screen on the window. Do you have screens where you live at home to keep up bugs for example.
• So the screen only works if it's small enough to keep up with the bugs. So if you want to be able to represent the bugs or things in the screen, we don't want the objects we're trying to represent to be able to fall through the cracks so to speak. That's not the technical definition. But does that help make sense of it? So if we think about the frequency, the spatial resolution how many samples we're taking. samples should be should the distance between samples should be half the smallest object we want to capture and what is quantization? We haven't talked about quantization yet.
• This is how many bits
• so if we have four bits like the card trick, then you can store 16 values. And if we have to arrange if we have 24 bits then we can store 24 So pardon me 16 point 7 million colors.
• I want to this TLA stands for three letter acronym for three letter abbreviation I guess more particularly anyway that that came up in class last year, so don't prepare for that. What are homogeneous coordinates and why are they important? Window and viewport.
• What's the advantage of WebGL when it comes to interaction because we can but we can also make use of HTML. We just go again to the Document Object Model to attach callbacks and so on.
• So this one was about just how are things organized in the HTML and the JavaScript files
• we did? We haven't been shading yet. Should you have known that? Okay, what are triangle strips and why are they important? That's a possible because we've talked about that might compare triangle strips and triangle fans
• Why is the flattened function required in our code
• and this 13 Does maybe a little bit of what we just talked about. What's the purpose of a Zed buffer or a depth buffer? We've talked about that a little bit too I think.
• So that's what we did last year. So you can see which ones we're not going to touch. If you have suggestions about questions on the exam, that would be a fair assessment of learning to date. All except them until Friday at noon. Okay, that's CMRA
• okay. There are no objections will will dismiss for today. Oh, it's one minute early. So as my writing the size of my writing, okay, here at the end
• this is not good.
• Relation values hue See
• ya know context is important right
• we don't have the whole chapter by it's only the part where like you describe last.
• We talked about the beginning of class today.
• So is it finished? No. It's not. It's not the whole time.
• Yeah, but we're not gonna. I'm not gonna ask you good stuff. It's in chapter five that we haven't talked about. Once no including some of the ideas from like specifying the viewing coordinates and and the perspective projection transformations. I won't make them
• I'll make them like our discussion. Not not more difficult. Anyway.
• I'll do my best to be considerate. Okay. Those were some some very good marks
• Yeah, I don't want you to do badly. That's why I welcome your input. Okay, thank you. And I'll make this reappear on the website. Once they get back to my office, are you gonna ask questions from this? So
• I think it's very vital to just ask for the question. Let's do that. On Friday afternoon for one hour and one hour will be question people will be late
• scattering.
• So I went over that. This is last year's midterm. So it was later in the year so it has more concepts than we've covered. So I went through last year's midterm as a way to give you an idea of the kinds of questions I would ask and as an invitation for you need to do suggest different questions that would be a fair assessment of what we've learned in the class. To date.
• Okay, now we're over time.
• Thank you for today. So when you come, we'll be re examined here. So try and spread out if you get here before me, I will be here early. Earlier than I have been before you guys Yeah, the car my car. Will be back in good shape by then or Yeah. Anyway, so see you Monday. Have a good weekend. I have office hours but if you have questions, get in touch with me please. Okay, thanks. Today.
• I saw your new laptop is missing a sticker went to a developer's conference. So got one so what it's a GitHub ice cream
• Yeah, Octocat is an ice cream. I thought it was Oh no. Ice cream with whipped. Yeah. Thank you.
• Thank you have a good day. Thanks, you too.
• You could just send him to me, just
• because just because I'm going to study last Monday, I was here but I couldn't reach it. I couldn't reduce the attendance. I'm not sure why. Last Monday I was here.
• Right now I saw that you sent me a contact request. Oh yeah. But I don't do that.
• Because you are courses contacts. are really strange, I think. I don't know. When I'm gonna get a message from a contact, I don't know, the context and so on. So I would just say send me email
• that would be better. I just, I don't want you to feel like I'm I'm snubbing you or anything? It's just I don't do it for anybody.
• It's okay. Last, last Monday, I was about to ask this, this attendance. So I just send request content in your Course.
• by Professor bye have a good day.
• Thank you. Professor. You're welcome.
• Thank you. Professor. You're welcome.

Responses

What important concept or perspective did you encounter today?

• The most important thig that I learned about the solution of previous year mid questions paper, in which most interesting solution for the question about Starting from black, how to get to the colour white, using the 3 primitive colours? and from white and went to black?
• The relation between the continuous, discrete, sampling, and quantization and the way how go from white to black and the reverse from the cube with the colors lines.
• The way WebGL is referenced and what forms a view using the point of view, vertices and the up vector.

Was there anything today about which you would like to know more?

• I would like to know more about view coordinates and vectors.
• Can I answer that vertex and fragment shader for this question? - "How do we indicate that webGL Program?" My understanding is vertex is for the geometry data and fragment is for texture of the graphic. So, they indicate as a webgl program ?