Mtg 18/25: Wed-08-Nov-2023

Outline for Today

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fish
this is not the actual struggle.
So we have a candidate here today and tomorrow for a job
talk in computer science so I was just at her research
presentation, which is going to have a teaching presentation
tomorrow afternoon at one o'clock I believe. So if you're
interested in that maybe
the way it's not a requirement,
it's going to be in this course or
No, I'm not sure the room number. I can send you a message
if you like. It's
like the very the short list it comes in, get there. So
there's two two candidates who are visiting this week. Not this
week and next week.
And most of them will be selected.
Or maybe they are like they're they're getting like they're
applying for a job here or like they're going to promote jobs.
No, they've applied for a job here. Amongst all the
applications you received, you identified two people who are
able to come and work here and who are seem to be a good fit
with our department with our needs. So they so when a
candidate comes, they give a research presentation and a
teaching presentation and the meet, meet the dean and
different things. Does
it include any survey like how did he perform or anything like
that?
Well as the dean solicits input from people
anyway
so I wanted to say first of all
did you get this email about an event tonight? Ritual
presentation
this morning?
Presenter is an alumna from our department she did her Bachelor
of Science honours in 79. She worked for SOS cow for over 30
years. Oh, she's Yeah. Okay, so I don't have to find insanity
okay.
So if you're interested, my talks about issues. I think
she'll talk about the issues in becoming certified, a certified
IT professional in Canada. And the benefits and
responsibilities of that, I guess. I think she also wrote a
book. Yes. She did. You read the email as well.
It's just not coming into my mind.
Okay, so let's talk about the midterm.
We'll go through your questions. One by one, just talk about the
exam questions. And then you can ask and we can discuss things
need discussing.
think there were 14 questions.
44 marks
so there's one question I think that most people didn't get. So
I'm the one former question so I decided to mark it out of 40
I did. A little other nice things in your favor.
So your courses
you see
okay
so great scope. So what I did for marking so it's a website
that lets me organize my marking by question. So I scan all the
exam papers. I upload them and then the software I can identify
students so it can it helps me to match students with papers.
And then I go through I've marked question one and then I
once I graded so with the question, I can set up a rubric.
So how I'm going to assign marks and then I can select the
criteria that are met for each assignment answer. And then I
can jump through the questions so I can mark off question one
and mark all of question two and so on.
Yes, if somebody like if somebody had given the answer in
a very good way very descriptive. So the rubrics will
be set on the answer of that particular student and he will
all be graded with respect to his answer. That is it how it
works.
I suppose it could work that way. But no. So I have an
answer. in mind. So I, I've identified things that I want to
see in the answer.
But if your answer is compelling, but not doesn't fit
with the way that I would have answered it still gives you
marks so it's not I don't want to say it's not. So the rubric
is a way for me to make clear some comments are some a clearer
what's being graded on and it saves you from having to read my
handwriting which might be a big advantage
so I mean we I set up the rubric so that we can
according to to my feelings about how the answer should be
constructed and then as I encounter differences, different
answers, I can add cases to handle them. So it's not a
matter of you have to have all checked off to get full marks.
Each of them have a certain number of points associated
stuff. It's checked off and you get that number of points. So if
you're six marks for a question,
then you may there may be three parts with two marks each. There
may be two parts or three marks each. So sometimes I also gave
full marks but then I deducted a point because it was mostly
correct but not quite there.
So I tried to explain those things in comments. So the other
so the one nice The nice thing for me as an instructor is that
I can
let you finish the sentence you think
the instructor like your navy great scope as an instructor.
So I'm using grade scope as a way to help me help support my
marking. So lets me go through the exams because we organize
them and lets me make comments about exams without reading on
the paper that you very capably filled to the brim with writing
yourself
so the other thing was a great scope. is.
So identify
so that's why I have a box with a certain number of lines in it
also space was not enough for that concerns. You know, we
needed more space or on
Well, I would say
you probably wrote more than he needed to for the answers. Maybe
you
ran out of the space
it was good maybe for the final give you some space, some extra
interest, some paper to do some rough planning of answers if you
like maybe
one time for each question with just one line more
I think like that take it under advisement. Thank you so anyway,
this is what I'm going to
I'm looking at what's in the box, or what's what I can see
what I'm focused on this part of the display. Anyway so there's
that so the other nice thing is if you have questions about the
marking, you can use grade scope to ask me to look at an answer
again. And then I can manage my response to you using grade
scope. So I think that's a nice way to facilitate because then I
can you can explain the question you have. Say, I think I gave
you the right answer here because of the following. You
look at it again. I'm sorry.
And then I can answer and then the whole thing. The other thing
I won't do is I have to update I'll have to trance marks change
enough to update your courses
so that you can but then you have evidence to bug me about.
You said that I got an extra mark here. Let me see reflected
on your courses anyway, I'm not saying I'm not going to give you
a marketing forget about I don't want to create a worst case
scenario for you.
So just say that so the grade school can be used to question
my grading. Just say mark the whole thing again.
Ask you to give reasons.
Okay CMRA
actually maybe I'll just write on the board
probably regret that decision. Okay. So
so John to the pixel. I let you off a little bit with this
because really an answer and B
doesn't have any
that's technically sufficient to answer the question. So. So I
think I gave you four marks. If you said something like that?
So these are some of the things that you might include we're
talking about a pixel I'm there were some comments about
physical being physical storage
I would say that's that's not a productive way to think about
it. Any questions or concerns about that? Is it helpful for me
to go through the questions?
Okay. So the next question was about.
Starting from black and going to wait
save you from having to see redraw. So we can locate if you
start with black here then we can get to white by adding
Yes What's that look like? So you can go from
Sophie Have you ever normalized values or if we think about the
the eight bit colors we can go from 000 to 55.
So I wanted to not be too strict about saying
start with white paper.
Was the same car
getting CMYK?
This that would be white
so I know this is this is black, for black and for cyan, magenta
and yellow. We have to have history really muddy. Imager for
printing all four inks of full intensity but I
thought this was I think this is a preferred answer compared to
yes where the cyan magenta. And yellow Lovers don't change
so this
and I think I gave some marks for saying to go from white to
black keys, subtract instead of add the RGB on the display.
Which I didn't mean to allow the room for an answer when I
realized the question permits something like that. So it makes
sense Okay.
So the concept of discrete continuous sampling and
quantization?
So maybe it's not enough to say continuous is so real world
phenomena are continuous
so I'm not saying that the answer has to be just like this,
but this is the way I was thinking about to sample them.
Once you sample them like for audio CD it's 44,100 times a
second
right
in order to do that, so what's the most efficient way to
reconstruct the samples, the phenomenon that we're sampling
some multiple of what
can you repeat your question? What is sorry, I wrote sample
them it's efficient rate to reconstruct them.
So what's this? What's the rate or for sampling at a particular
rate? What's the what's how accurate can reconstruction be?
So for the audio example, we sampled 44.1 kilohertz. What do
humans hear? Generally, what's the highest frequency people can
hear? Yeah, so people can generally hear up to about
22,000 hertz so we sampled twice the highest we could highest
frequency want to reconstruct. That wasn't part of the
question. I'm just trying to connect back to our discussions
in class. Okay, so we've taken care of discrete continuous
sampling
and quantization refers to
refers to the precision with which we store the samples.
So if we have four bits, how many levels can we store? No.
One we have one bit, we can store two, four bits we can
store 16 levels
so adding bits we can store
to the end
easy and distinct values. So it makes sense.
I have a question about the quantization. So the explanation
is what you wrote, right? I, the point is, in this question, I
ran out of the space and I go down the page. I'm not sure if
you saw that or not because actually you deduct the grade
for the Constitution from me.
And it just Okay, so we like
this at the end of the page. I'm not sure if you saw it or not.
Okay, so asked me to look at that. Okay.
Okay, so far. So good.
KT x again
next fly W
so why is that useful? For computer graphics?
So you can unify this, the transformations for rotation,
scaling and translation
perspective transformation. Is it the same or not?
Yeah, so, not so.
Whatever the transformation need to do if we use a foot three
dimensional trend, we have homogenous homogeneous
coordinates of three dimensions. So, we have four by four
matrices. So, the matrix can we have a single matrix that
includes the scaling and rotation translation so, we
don't have to have a separate
we don't have to deal with the translation separately
so, in 2d It's a three by three matrix 3d four by four matrix
Okay,
that's too small.
So when doing viewport so the text would say the window is in
world coordinates. Or graphics texts will say when.
transpose the same world coordinates and device
coordinates well to text Edward Angel says there's lots of
different ways to think about Windows. It's part of it's a
very overused term in computers. So I wasn't I wasn't focused on
the window part. Just tried to get the idea of.
That's displayed
okay that care
where's the camera?
So I was thinking about
because you're on the web, we can use facilities within HTML
to provide our interaction device or interaction controls
do that?
So there's, we had that discussion about the old way of
doing interaction was polling and the modern ways events, cook
event callbacks and so on. So if people if you wrote something
that was reminiscent of the old way and modern approach I gave
you marks for that.
statement like that. You get context. So that's what I was
looking for.
So this next one. I wanted you to talk about pieces appear in
the HTML files and the JavaScript files that we've been
looking at from the tax.
Hope it didn't throw you off because I met at a table in
question. And then write text check checker. Science
misspelled text
anyway, so what do we have needs to know
have to Canvas
Canvas
interface components
What else do we have in the shaders?
So I'm not sure how prevalent or is his use of his style of
putting shaders into the HTML and identifying them as scripts.
So a lot of examples they see the shader code is put into a
text variable. And then that's compiled from there. We're
talking about the text. And we've talked about the examples
in the text a lot. And they're online, on my website and on the
interactive computer graphics.com website. So I hope
it wasn't confusing about what what was intended here.
So the JavaScript we have
with GL context.
So the WebGL context code associated with the canvas.
Events twice let me just try that again.
Anything else
okay so that makes sense
see if I have to say no no I kept it okay
okay.
So reduces triangles etc so vertices.
So if we specify if we want to draw triangles we need to
specify three vertices for each triangle we want to draw so,
that can be an efficient
strangle strips are more efficient because they string
together
right this
this is makes
So, you don't need to see me draw and try and write down in
words. But I can just do it the picture there if that makes
sense. So, so if you talked about things
talked about each of the four things but didn't say anything
about relative efficiency then I took off half a mark the
efficiency
data application Yeah. I have the same problem with the other
like the other question.
You've had another piece of your
answer I think you haven't seen the fans because it says that
there's no description for the fans but it's
okay. So add that to the list of questions you're gonna ask me to
look at okay. You're all seem okay.
So connecting to shaders. I was looking for something that's
where you send attributes vertex attributes.
Use them to capture information that can change between vertices
and then uniforms
so don't change those values in the shader. We're not varying
them with vertices. We're just
doing one supplying one value so that's what I had in mind. One
or two people. Kind of close to that I think. But anyways,
that's why I marked it at a 40 instead of 44.
And to make up for some other issues along the way. Okay,
sharpened over here.
So I was thinking of something along the lines of an advantages
that lets you do use WebGL without getting into the details
of writing of compiling shaders and doing many other mundane
things that you'd have to do on a jet Web GL program. And the
disadvantage is that maybe it's got a steep learning curve or
it's only on the web, it's not a desktop environment. So I, I try
to be open about these. So if you said this was an advantage I
searched I've tried to get I use Google to help me decide whether
they really advantages or not. And what else so come up with
mentioned about plugins, you don't need plugins. The example
that I had mine was the morbid controls we used in that one
example which is an add on that needs to be specified. So I took
that as a plugin. So I may deduct deducted half a mark I
think for that.
An H So flatten YFL looks like an H two let's try that again.
Close enough to flatten okay.
I think when you change your tracking it's very more better.
Compare these two boards together. This is better Yeah,
way too much.
It's too much better. Maybe I should do anyway. Okay, so
flatten
so we so the authors are using JavaScript features like.
Push elements into view, right? When I'm doing positions, for
example, or some other when we're populating the race we do
this so that creates
so the extra info is stored to support this.
So we're just using fun so I'm really dealing with I can do
better than that
so better
so what's your agenda second line, extra info store to
support
support this
is provided
So object coordinates are transformed the camera
coordinates by the modelview matrix. The camera coordinates
are transformed to clip coordinates via the projection
matrix.
That's the kind of thing I was looking for. So I think I was
generous in in in grading that if the basic structure was there
and then 14.
That's not fair. So what's its purpose?
Or height? Hidden? Surface Removal Yeah.
So how does it work?
It is used for depths information for 2d rendering. It
is choosing which objects should be on top of the other one.
Yeah, but that description is gives a little bit is a little
vague. So for every pixel every item as we're rasterizing it,
each fragment each pixel we generate we get a depth
information with so the depth buffer is storing if, if the
newly generated pixel is closer than the one that's stored then
we replace that the new def value or replace the old def
value with a new one. So we're just keeping track of the depth
of each pixel that gets rasterized once we've completed
then what we see is just image generated by the visible
surfaces are determined because they're the closest to the
viewer. So that makes sense. I know I'm out of time here so I
don't want to keep you too long.
So keep only the closest that's fine. I'm writing a little
smaller there
five minutes late here so it's going to tell you about
assignment three. I'll put it online today. Some supporting
material. And then I'll give you a choice about exit due dates.
Are the last Okay, thank you. Thanks for today
you can tell people who weren't here that we discussed important
final exam information
or whatever you would like to say to them Okay, so this is a
exam is a formative evaluation so you can see how you're doing
with the material
and where there might be some room to improve and if you have
questions, let me know. I'm available. Okay. And if you're
free tonight, you might want to check out that presentation
about which you've already received email Okay, thanks
again. Take care
welcome. Thank you.
Thanks, you too.
Thanks, you too.
Thanks, you too.

Responses

What important concept or perspective did you encounter today?

I liked how professor cleared out the midterm questions. Now I know how he wants the questions to be answered. Hopefully this will be helpful in final term
The most important thing in today's class was discussing the whole midterm and it was really informative because I learned Abt my mistakes.
I thought Q8. from midterm 'texr' was a typo. Sorry that I confuse.

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