| Re: Object Graphics newbie question [message #25180] |
Fri, 25 May 2001 14:37 |
Dick Jackson
Messages: 347
Registered: August 1998
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Senior Member |
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[sorry, that first message slipped out before I was done!]
Hi Arend,
"Arend Sluis" <sluis@physics.rutgers.edu> wrote in message
news:3B0E7558.8EA29250@physics.rutgers.edu...
> I want to make a 2D plot of, say, 10k data points, and each data point
> has associated with it a specific color and a set of secondary data
> points (an emission line spectrum). Since I want to be able to zoom in
> on and move around the data in order to make selection of individual
> data points easier, I thought that Object Graphics would be the way to
> go. However, it is 10k data points, so I clearly need to be careful in
> order to have efficient code.
>
> My first question is: should I be using Object Graphics
It may be overkill for the project as you've described, but the XObjView
example program is a great starting point for a 3D viewing/inspecting
application. If there's a useful way to turn your data into a 3D display of
some kind, this may be especially helpful. Your mention that each point in
2D has a spectrum associated with it suggests that some 3D representation of
the whole dataset at once may be possible. (or it may be just a mess)
Here's an example of how easy XObjView is to use (code examples are attached
to this message as .pro files... hope it works for you):
=====
m=obj_new('IDLgrSurface', Dist(30), Color=[255,0,255], Style=2, $
Shading=1, Name='Wide Magenta Surface')
g=obj_new('IDLgrSurface', Dist(10)*5, Color=[0,255,0], Style=2, $
Shading=1, Name='Tall Green Surface')
xobjview,[m,g]
=====
You've got viewing controls, and a select tool which presents the name of
whatever object you click on. If you want to do something else when an
object is clicked, you might modify the code in idlexobjviewwid__define.pro
around line 406. (I've done a bit of work extending these classes for my own
purposes, but be warned: they are not documented, and I believe they are
subject to change without notice.)
Now, a reality check shows that 10,000 separate objects (so that each is
selectable with the Select tool), even if they are just points, is a lot for
Object Graphics to handle.
=====
a=objArr(10000)
oSymbol=obj_New('idlgrsymbol',3)
for i=0,9999 do a[i]=obj_new('idlgrpolyline', $
RandomU(seed,3,1)*100, $
symbol=oSymbol, $
name=StrTrim(i,2))
xobjview,a
=====
(mine took 17 seconds to redraw while rotating)
But one IDLgrPolyline object with 10,000 points is a breeze!
=====
oSymbol=obj_New('idlgrsymbol',3)
b=obj_new('idlgrpolyline', $
RandomU(seed,3,10000)*100, $
Symbol=oSymbol, $
Linestyle=6,Name='One big object')
xobjview,b
=====
This is where you might want to customize what happens when you click on the
object, perhaps to report the location of the point you clicked on (add this
in idlexobjviewwid__define.pro before the 'endif' on line 409):
pickedOK = self.oWindow-> $
PickData(oCurrent, oSelected[0], $
[event.x, event.y], pickXYZ)
Print, pickXYZ
Recompile it, click on a point and see the output log. A bit crude, but you
get the idea.
If black points aren't enough, each datum can of course be represented by a
polygon, a smoothly colored line, or whatever you please. The graphics
classes really give you a lot of options. A colored point scatterplot can be
done as follows:
=====
oSymbol=obj_New('idlgrsymbol',3)
c=obj_new('idlgrsurface', $
DataX=RandomU(seed,100,100), $
DataY=RandomU(seed,100,100), $
DataZ=RandomU(seed,100,100), $
Style=0,Vert_Colors=RandomU(seed,3,10000)*256, $
Name='One big object')
xobjview,c
=====
(yes, we'd prefer to use a vector of 10000 for DataX|Y|Z, but IDLgrSurface
really wants a 2D array)
Well, that was quite a ramble. Hope it's of some help.
Cheers,
--
-Dick
Dick Jackson / dick@d-jackson.com
D-Jackson Software Consulting / http://www.d-jackson.com
Calgary, Alberta, Canada / +1-403-242-7398 / Fax: 241-7392
begin 666 ex0.pro
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@<F9A8V4G*0T*>&]B:G9I97<L6VTL9UT-"@T*96YD#0H`
`
end
begin 666 ex1.pro
M83UO8FI!<G(H,3 P,# I#0IO4WEM8F]L/6]B:E].97<H)VED;&=R<WEM8F]L
M)RPS*0T*9F]R(&D],"PY.3DY(&1O(&%;:5T];V)J7VYE=R@G:61L9W)P;VQY
M;&EN92<L("0-"B @(" @(" @(" @(" @(" @(" @(" @(" @(" @4F%N9&]M
M52AS965D+#,L,2DJ,3 P+" D#0H@(" @(" @(" @(" @(" @(" @(" @(" @
M(" @('-Y;6)O;#UO4WEM8F]L+" D#0H@(" @(" @(" @(" @(" @(" @(" @
M(" @(" @(&YA;64]4W1R5')I;2AI+#(I*0T*>&]B:G9I97<L80T*#0IE;F0-
!"@``
`
end
begin 666 ex2.pro
M;U-Y;6)O;#UO8FI?3F5W*"=I9&QG<G-Y;6)O;"<L,RD-"F(];V)J7VYE=R@G
M:61L9W)P;VQY;&EN92<L("0-"B @(" @(" @("!286YD;VU5*'-E960L,RPQ
M,# P,"DJ,3 P+" D#0H@(" @(" @(" @4WEM8F]L/6]3>6UB;VPL("0-"B @
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2;V)J=FEE=RQB#0H-"F5N9 T*
`
end
begin 666 ex3.pro
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@:6<@;V)J96-T)RD-"GAO8FIV:65W+&,-"@T*96YD#0H`
`
end
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| Re: Object Graphics newbie question [message #25183 is a reply to message #25180] |
Fri, 25 May 2001 13:14  |
Dick Jackson
Messages: 347
Registered: August 1998
|
Senior Member |
|
|
Hi Arend,
"Arend Sluis" <sluis@physics.rutgers.edu> wrote in message
news:3B0E7558.8EA29250@physics.rutgers.edu...
> I want to make a 2D plot of, say, 10k data points, and each data point
> has associated with it a specific color and a set of secondary data
> points (an emission line spectrum). Since I want to be able to zoom in
> on and move around the data in order to make selection of individual
> data points easier, I thought that Object Graphics would be the way to
> go. However, it is 10k data points, so I clearly need to be careful in
> order to have efficient code.
>
> My first question is: should I be using Object Graphics
It may be overkill for the project as you've described, but the XObjView
example program is a great starting point for a 3D viewing/inspecting
application.
I'd say "certainly give it a try," with a first attempt by using the
XObjView example program. I think it's a great starting point, and here's an
example of how easy it is to use:
IDL> m=obj_new('IDLgrSurface', Dist(30), Color=[255,0,255], Style=2,
Shading=1, Name='Wide Magenta Surface')
IDL> g=obj_new('IDLgrSurface', Dist(10)*5, Color=[0,255,0], Style=2,
Shading=1, Name='Tall Green Surface')
IDL> xobjview,[m,g]
You've got viewing controls, and a select tool which presents the name of
whatever object you click on.
I don't know
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| Re: Object Graphics newbie question [message #25185 is a reply to message #25183] |
Fri, 25 May 2001 11:02 |
Rick Towler
Messages: 821
Registered: August 1998
|
Senior Member |
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> My first question is: should I be using Object Graphics? I have no feel
> for how complicated it would be to implement the
> zoom/translate/selection features in Direct Graphics.
This depends greatly on how you decide to navigate. Using idlgrmodel's
built in methods the best you can accomplish is something similar to the
flythrough in the demo programs. If you have used this you know how much
this approach sucks.
I have written a camera object that allows intuitive control of object
graphics scene composition based on the camera (or viewer location) and
either pitch, yaw and roll values or a lookat point. I am planning on
making it publicly available soon, but if you wish I could send you the .pro
files. You will have to put up with incomplete documentation and since you
would be the first person other than myself to use the objects I would ask
that you provide some feedback so I can work out any kinks before I set
these guys free. With that said, object is simple to use so I don't think
that would be too painful.
>
> My second question is: Suppose I should use Object Graphics, should I
> use IDLgrPolygon for each data point, or should I try to do this using
> IDLgrPlot with a self-defined IDLgrSymbol (I want a filled symbol in
> order to see its color clearly). The "Objects and Object Graphics" IDL
> manual gives both as a possibility, but I am unclear on the relative
> merits of each.
>
This is a good question and unfortunately I can't tell you what the most
efficient approach would be. Since you want to select each object you'll
have to define each object individually. It would be easier to go the plot
approach since using the polygon object you would have to define each vertex
in the symbol explicitly (instead of just defining the center). Maybe define
50 or 100 objects using each approach and look to see how much memory the
objects consume. I would assume they would be different, maybe one is
significantly different? For a symbol, I would define a 3d diamond. It
would only have 8 triangles which I think is as cheap as you can go.
On rendering speed, this will be totally platform dependent. I routinely
render scenes with over 150k triangles at 5-10 frames per second on a 700
MHz x86 with an Nvidia Geforce DDR graphics card. This is certainly fast
enough to navigate through in real time. The same program running on our
sun ultra 60 + creator 3d does maybe .5-1 frame per second, way too slow to
navigate in real time. In my case around half of the triangles comprise a
terrain model whose connectivity array is optimized. I would guess shoving a
lot of little objects down the renderers throat would be less efficient.
-Rick Towler
Fisheries Acoustics Lab
University of Washington
School of Aquatic and Fishery Sciences
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| Re: Object Graphics newbie question [message #25187 is a reply to message #25185] |
Fri, 25 May 2001 08:50 |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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Arend Sluis (sluis@physics.rutgers.edu) writes:
> I want to make a 2D plot of, say, 10k data points, and each data point
> has associated with it a specific color and a set of secondary data
> points (an emission line spectrum). Since I want to be able to zoom in
> on and move around the data in order to make selection of individual
> data points easier, I thought that Object Graphics would be the way to
> go. However, it is 10k data points, so I clearly need to be careful in
> order to have efficient code.
Unless you have one of those new wall-size monitors
from Sony, I would be a bit careful in visualizing
10K data points! In fact, I think I would spend just
a bit more time contemplating the difference between
analyzing the data and visualizing it. In this case,
I'm pretty sure I might choose a different method for
visualizing 10K points than I would for visualizing,
say, 100 of those 10K points. In fact, I might even
do it in two separate windows: an "overview" and a
"zoom" window, for example.
> My first question is: should I be using Object Graphics? I have no feel
> for how complicated it would be to implement the
> zoom/translate/selection features in Direct Graphics.
Selection might possibly be easier in object graphics,
but everything else is likely to be MUCH harder, depending
upon how familiar you are with it. Zoomimg and translating
are pretty much the same in either system.
> My second question is: Suppose I should use Object Graphics, should I
> use IDLgrPolygon for each data point, or should I try to do this using
> IDLgrPlot with a self-defined IDLgrSymbol (I want a filled symbol in
> order to see its color clearly). The "Objects and Object Graphics" IDL
> manual gives both as a possibility, but I am unclear on the relative
> merits of each.
I think I would use a symbol rather than a polygon, but
just because the infrastructure is already in place to
handle symbols. I'm pretty sure a symbol *is* a polygon
to the object graphics system, so I doubt you will take
a performance hit. I doubt you will need 10K symbols,
however. Try to limit the number of things you build,
so you don't take all day to render it. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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