ing ways to leverage simulation results from ladybug and inform design of building envelops with benefits that can be modeled. Given 20 percent of the cost of a project typically goes to the facades, and maybe a half of that goes to the openings, there is a good enough reason to question how to materialize that 10 percent, which can result in 10-30 percent difference in total energy comsumption.
I think ideally radiation analysis, natural ventilation and daylight analysis on floors should all inform opening sizes and placements, as well as the building sections at large. However natural ventilation seems to be the most complicated one because it couples airflow and thermo dynamics. I have a definition setup so that I can batch simulations for radiation analysis and daylight analysis, but natural ventilation is the missing link. So for what I am doing now I will select a handful of design that seem to work the best based on the two available analysis and convert all the geometry into CAD files so that I can run them in an evaluation copy of autodesk simulation CFD. So for now I can do this in 2 stages.
But for the future, given the possibility of actually have that as a part of grasshopper feature, which would be lovely, I want to understand the science behind it and share some links.
(http://www.wbdg.org/resources/naturalventilation.php) In this link the author outlines quite a few general principles and variables to consider for natural ventilated buildings.
For example, how stack effect works.
Qstack = Cd*A*[2gh(Ti-To)/Ti]^1/2, where
Qstack = volume of ventilation rate (m³/s)Cd = 0.65, a discharge coefficient.A = free area of inlet opening (m²), which equals area of outlet opening.g =9.8 (m/s²). the acceleration due to gravityh = vertical distance between inlet and outlet midpoints (m)Ti = average temperature of indoor air (K), note that 27°C = 300 K.To = average temperature of outdoor air (K)
The thing about natural ventilation is that not only the sizes and positioning of openings of the facade facing predominant wind matter, but also the openings on the other side matter. The vertical distance between the inlets and outlets also need to be taken into account. The author suggests that naturally ventilated buildings should be no wider than 45 feet.
and in this pdf presentation it discusses CFD for natural ventilation and illustrates why it is not easy
http://isites.harvard.edu/fs/docs/icb.topic882838.files/L17.6205Airflow-Modeling_Ibarra.pdf
and in this pdf briefly outlines the approach taken by designbuilder
http://isites.harvard.edu/fs/docs/icb.topic472869.files/DesignBuilder%20Simulation%20Training_HSD.pdf
Lastly a wide spectrum of environmental analysis works by e3lab
http://www.e3lab.org/research
http://www.e3lab.org/green-buildings
If I make progress on a way to tie the three analysis together (radiation, daylight and natural ventilation), I wont forget to post it on this thread.
Thanks.…
The PC actually stops working because after a few seconds the simulation starts the fan inside the PC all of a sudden stops and for the next 5-10 mins I cannot do anything, even alt+ctrl+canc. After I wait for that time i get the followig error:
the ReadMe says:
{0;0;0}0. Grid-based Radiance simulation1. The component is checking ad, as, ar and aa values. This is just to make sure that the results are accurate enough.2. -ar is set to 300.3. Good to go!4. Current working directory is set to: C:\Users\Luigi\Desktop\Prova__\Prova_1\gridBasedSimulation\5. Found a trans material... Resetting st parameter from 0.85 to 0.011276004966. WMIC PROCESS get Commandline7. WMIC PROCESS get Commandline8. WMIC PROCESS get Commandline9. WMIC PROCESS get Commandline10. WMIC PROCESS get Commandline11. WMIC PROCESS get Commandline12. WMIC PROCESS get Commandline13. WMIC PROCESS get Commandline14. WMIC PROCESS get Commandline15. WMIC PROCESS get Commandline16. WMIC PROCESS get Commandline17. WMIC PROCESS get Commandline18. WMIC PROCESS get Commandline19. WMIC PROCESS get Commandline20. WMIC PROCESS get Commandline21. WMIC PROCESS get Commandline22. WMIC PROCESS get Commandline23. WMIC PROCESS get Commandline24. WMIC PROCESS get Commandline25. WMIC PROCESS get Commandline26. WMIC PROCESS get Commandline27. WMIC PROCESS get Commandline28. WMIC PROCESS get Commandline29. WMIC PROCESS get Commandline30. WMIC PROCESS get Commandline31. WMIC PROCESS get Commandline32. WMIC PROCESS get Commandline33. WMIC PROCESS get Commandline34. WMIC PROCESS get Commandline35. WMIC PROCESS get Commandline36. WMIC PROCESS get Commandline37. WMIC PROCESS get Commandline38. WMIC PROCESS get Commandline39. WMIC PROCESS get Commandline40. WMIC PROCESS get Commandline41. WMIC PROCESS get Commandline42. WMIC PROCESS get Commandline43. WMIC PROCESS get Commandline44. WMIC PROCESS get Commandline45. WMIC PROCESS get Commandline46. WMIC PROCESS get Commandline47. WMIC PROCESS get Commandline48. WMIC PROCESS get Commandline49. WMIC PROCESS get Commandline50. WMIC PROCESS get Commandline51. WMIC PROCESS get Commandline52. WMIC PROCESS get Commandline53. WMIC PROCESS get Commandline54. WMIC PROCESS get Commandline55. WMIC PROCESS get Commandline56. WMIC PROCESS get Commandline57. WMIC PROCESS get Commandline58. WMIC PROCESS get Commandline59. WMIC PROCESS get Commandline60. WMIC PROCESS get Commandline61. WMIC PROCESS get Commandline62. WMIC PROCESS get Commandline63. WMIC PROCESS get Commandline64. WMIC PROCESS get Commandline65. WMIC PROCESS get Commandline66. WMIC PROCESS get Commandline67. WMIC PROCESS get Commandline68. WMIC PROCESS get Commandline69. WMIC PROCESS get Commandline70. WMIC PROCESS get Commandline71. WMIC PROCESS get Commandline72. WMIC PROCESS get Commandline73. WMIC PROCESS get Commandline74. WMIC PROCESS get Commandline75. WMIC PROCESS get Commandline76. WMIC PROCESS get Commandline77. WMIC PROCESS get Commandline78. WMIC PROCESS get Commandline79. WMIC PROCESS get Commandline80. WMIC PROCESS get Commandline81. WMIC PROCESS get Commandline82. WMIC PROCESS get Commandline83. WMIC PROCESS get Commandline84. WMIC PROCESS get Commandline85. WMIC PROCESS get Commandline86. WMIC PROCESS get Commandline87. WMIC PROCESS get Commandline88. WMIC PROCESS get Commandline89. WMIC PROCESS get Commandline90. WMIC PROCESS get Commandline91. WMIC PROCESS get Commandline92. WMIC PROCESS get Commandline93. WMIC PROCESS get Commandline94. WMIC PROCESS get Commandline95. WMIC PROCESS get Commandline96. WMIC PROCESS get Commandline97. WMIC PROCESS get Commandline98. WMIC PROCESS get Commandline99. WMIC PROCESS get Commandline100. WMIC PROCESS get Commandline101. WMIC PROCESS get Commandline102. WMIC PROCESS get Commandline103. WMIC PROCESS get Commandline104. WMIC PROCESS get Commandline105. WMIC PROCESS get Commandline106. WMIC PROCESS get Commandline107. WMIC PROCESS get Commandline108. WMIC PROCESS get Commandline109. WMIC PROCESS get Commandline110. WMIC PROCESS get Commandline111. WMIC PROCESS get Commandline112. WMIC PROCESS get Commandline113. WMIC PROCESS get Commandline114. WMIC PROCESS get Commandline115. WMIC PROCESS get Commandline116. WMIC PROCESS get Commandline117. WMIC PROCESS get Commandline118. WMIC PROCESS get Commandline119. WMIC PROCESS get Commandline120. WMIC PROCESS get Commandline121. WMIC PROCESS get Commandline122. WMIC PROCESS get Commandline123. WMIC PROCESS get Commandline124. WMIC PROCESS get Commandline125. WMIC PROCESS get Commandline126. WMIC PROCESS get Commandline127. WMIC PROCESS get Commandline128. WMIC PROCESS get Commandline129. WMIC PROCESS get Commandline130. WMIC PROCESS get Commandline131. WMIC PROCESS get Commandline132. WMIC PROCESS get Commandline133. WMIC PROCESS get Commandline134. WMIC PROCESS get Commandline135. WMIC PROCESS get Commandline136. WMIC PROCESS get Commandline137. WMIC PROCESS get Commandline138. WMIC PROCESS get Commandline139. WMIC PROCESS get Commandline140. WMIC PROCESS get Commandline141. WMIC PROCESS get Commandline142. WMIC PROCESS get Commandline143. WMIC PROCESS get Commandline144. WMIC PROCESS get Commandline145. WMIC PROCESS get Commandline146. WMIC PROCESS get Commandline147. WMIC PROCESS get Commandline148. WMIC PROCESS get Commandline149. WMIC PROCESS get Commandline150. WMIC PROCESS get Commandline151. WMIC PROCESS get Commandline152. WMIC PROCESS get Commandline153. WMIC PROCESS get Commandline154. WMIC PROCESS get Commandline155. WMIC PROCESS get Commandline156. WMIC PROCESS get Commandline157. WMIC PROCESS get Commandline158. WMIC PROCESS get Commandline159. WMIC PROCESS get Commandline160. WMIC PROCESS get Commandline161. WMIC PROCESS get Commandline162. WMIC PROCESS get Commandline163. WMIC PROCESS get Commandline164. WMIC PROCESS get Commandline165. WMIC PROCESS get Commandline166. WMIC PROCESS get Commandline167. WMIC PROCESS get Commandline168. WMIC PROCESS get Commandline169. WMIC PROCESS get Commandline170. WMIC PROCESS get Commandline171. WMIC PROCESS get Commandline172. WMIC PROCESS get Commandline173. WMIC PROCESS get Commandline174. WMIC PROCESS get Commandline175. WMIC PROCESS get Commandline176. WMIC PROCESS get Commandline177. WMIC PROCESS get Commandline178. WMIC PROCESS get Commandline179. WMIC PROCESS get Commandline180. WMIC PROCESS get Commandline181. WMIC PROCESS get Commandline182. WMIC PROCESS get Commandline183. WMIC PROCESS get Commandline184. WMIC PROCESS get Commandline185. WMIC PROCESS get Commandline186. WMIC PROCESS get Commandline187. WMIC PROCESS get Commandline188. WMIC PROCESS get Commandline189. WMIC PROCESS get Commandline190. WMIC PROCESS get Commandline191. WMIC PROCESS get Commandline192. WMIC PROCESS get Commandline193. WMIC PROCESS get Commandline194. WMIC PROCESS get Commandline195. WMIC PROCESS get Commandline196. WMIC PROCESS get Commandline197. WMIC PROCESS get Commandline198. Runtime error (IndexOutOfRangeException): index out of range: 0199. Traceback: line 320, in script
The thing is that if I raise the -aa parameter from 0.05 to 0.1 all works fine..
Is this only related to my PC then?? What should I do to solve this issue?
Thanks again for your help
Luigi…
is an emerging research area that exploits the principles and logic of natural systems in the design of the built environment. Sandworks* investigates the development of a computational design system informed by the sand self-formation behaviour. The knowledge objective is to understand the process of coding the material physical behaviour that follows the geometrical constraints of developable, ruled and hyperbolic surfaces formed by sand. Through physical and digital form-finding exercises, the workshop will explore the relationships between material and its shaping processes in the generation of form in parallel to theoretical lectures and discussion on cutting edge approaches of computational thinking, design and fabrication in architecture and design. Participants will be introduced to ruled based design thinking through digital design and fabrication systems as well as physical modelling and prototyping techniques.. The workshop aim is to provide an understanding framework of how such processes occur in nature and find their translation in the design of the artificial. *This research started at the Architectural Association school of architecture in London exploring the design and fabrication techniques of sand tectonic system and now it is pursued at ENSA Paris-Malaquias focusing on the development of the machinic morphogenetic possibilities of sand self-formation with robotic distribution of material through addition, subtraction and deposition techniques.www.sandworks.org /// Application To apply, please follow this link to fill the application form https://docs.google.com/forms/d/1n_LN2svFTT79kCqndxznKRj4PX8J8__FVNKvjiHTeJU/viewform /// Fees* 1700 EGP for students / 2000 EGP for graduates and young professionals * 20 % discount for early registration and payment before 22 nd of August 2014 more info on the workshop webpage: http://www.encodestudio.net/#!sandworks/c1nn1…
ur setup. Can you say what sensor you are using? Are you using an Arduino to write this ascii information to the serial port? If so, there may be some formatting code for the string that you'll need to do to get the Read component to function properly. I see that you were able to open the port and Start reading... so my first thought is that the data is formatted correctly....
All of the read components look for a specific character (in this case two characters) to indicate when it has reached the end of the line being read and should spit out the data. In this case, Firefly uses the Carriage Return (\r) and Line Feed (\n) to know when it has reached the end of the line. In arduino, these are automatically added to any line if you use the Serial.println("blah, blah, blah"); command. Notice, this is different from the Serial.print("nothing to see here"); command. This doesn't mean that you can't still use the regular print command... it's just you need to use the println command to indicate when you've reached the end of the line. Let's take a look at a simple example.
void setup() { Serial.begin(9600);}void loop() { int sensorValue = analogRead(A0); Serial.print("The value of the sensor is: "); Serial.println(sensorValue);
delay(20); // important to wait some small time so you aren't sending just a ton of info over to GH which will cause it to crash :(
}
The first print statement prints a string to the serial port... and the next one adds the current sensor value... and THEN adds the carriage return and line feed to start a new line. The nice thing about using these together is that you can concatenate any type of data you want. If you were to upload this sketch, you should see a sentence being printed to the serial port that says "The value of the sensor is: 512". I made up the number, but you get the idea. Notice, I also had to include a delay function. You don't always need this (there are other ways to go about this) but the important thing to note is that the loop cycle on the Arduino can run really fast. I mean... really fast. So, you wont want to send so much data over to GH, because this could flood the string buffer in the Read component and cause it to crash (eventually). It's a good idea to add some small time interval just to slow it down a bit. I should say that I've optimized the refresh rate in the next release so it's significantly faster... so hopefully this wont be as big of a problem... but hopefully that helps some.
Now... Why are you writing data to a sensor? Sensors by default are considered inputs... so I'm quite confused as to why you would want to send data back (if you are... then you need some way to handle the string data being sent from GH... this is the whole reason we built the Firefly firmata... it sets up the two-way protocol so you don't have to deal with all of that mess... If you're going to read and write, you're better off just uploading the firmata and using the Uno Read and Write components). Also, I'm not very familiar with the Hyperterm or Advanced Serial Port Terminal... but I will say that could get COM conflicts if you're trying to open the port with different tools. Anyway, I hope some of this helps you get up and running.
Cheers,
Andy
…
rring to the above image)
Area
effective
effective
Second
Elastic
Elastic
Plastic
Radius
Second
Elastic
Plastic
Radius
of
Vy shear
Vz shear
Moment
Modulus
Modulus
Modulus
of
Moment
Modulus
Modulus
of
Section
Area
Area
of Area
upper
lower
Gyration
of Area
Gyration
(strong axis)
(strong axis)
(strong axis)
(strong axis)
(strong axis)
(weak axis)
(weak axis)
(weak axis)
(weak axis)
A
Ay
Az
Iy
Wy
Wy
Wply
i_y
Iz
Wz
Wplz
i_z
cm2
cm2
cm2
cm4
cm3
cm3
cm3
cm
cm4
cm3
cm3
cm
I have a very similar table which I could import to the Karamba table. But I have i_v or i_u values as well as radius of inertia for instance.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
dimensjon
Masse
Areal
akse
Ix
Wpx
ix
akse
Iy
Wpy
iy
akse
Iv
Wpv
iv
Width
Thickness
Radius R
[kg/m]
[mm2]
[mm4]
[mm3]
[mm]
[mm4]
[mm3]
[mm]
[mm4]
[mm3]
[mm]
[mm]
[mm]
[mm]
L 20x3
0.89
113
x-x
4,000
290
5.9
y-y
4,000
290
5.9
v-v
1,700
200
3.9
20
3
4
L 20x4
1.15
146
x-x
5,000
360
5.8
y-y
5,000
360
5.8
v-v
2,200
240
3.8
20
4
4
L 25x3
1.12
143
x-x
8,200
460
7.6
y-y
8,200
460
7.6
v-v
3,400
330
4.9
25
3
4
L 25x4
1.46
186
x-x
10,300
590
7.4
y-y
10,300
590
7.4
v-v
4,300
400
4.8
25
4
4
L 30x3
1.37
175
x-x
14,600
680
9.1
y-y
14,600
680
9.1
v-v
6,100
510
5.9
30
3
5
L 30x4
1.79
228
x-x
18,400
870
9.0
y-y
18,400
870
9.0
v-v
7,700
620
5.8
30
4
5
L 36x3
1.66
211
x-x
25,800
990
11.1
y-y
25,800
990
11.1
v-v
10,700
760
7.1
36
3
5
L 36x4
2.16
276
x-x
32,900
1,280
10.9
y-y
32,900
1,280
10.9
v-v
13,700
930
7.0
36
4
5
L 36x5
2.65
338
x-x
39,500
1,560
10.8
y-y
39,500
1,560
10.8
v-v
16,500
1,090
7.0
36
5
5
I have diagonals (bracings) which can buckle in these "non-regular" directions too, and they do. If I could add those values then in the Karamba model I could assign specific buckling scenarios..... I can see another challenge which will be at the ModifyElement component, I will not be able to choose these buckling lengths, in these directions.
Do you think this functionality can be added within short, or should I try to find another way to model these members?
Br, Balazs
…
greatly appreciate it!!
You can write the number of the question and write your answer next to it, example:
1) a
2) c
3) a) Washington University in St. Louis
4) 2 weeks (1week+1week shipping)
5) 130
6) b
7) b
The survey questions are as follows:
1)
Did you 3D print before?
5)
How much did it cost (in dollars)?
a.
Yes, for a school project
a.
Between 20 & 50
b.
Yes, for a personal project
b.
Between 50 & 80
c.
Between 80 & 120
2)
Print size
d.
Please specify if otherwise: _____ dollars
a.
Between 2 & 6 cubic inches
b.
Between 6 & 12 cubic inches
6)
Do you think the price was expensive?
c.
Between 12 & 20 cubic inches
a.
Not at all
d.
Please specify if otherwise: ____cubic inches
b.
A little bit expensive
c.
Very expensive
3)
Where did you print your object?
a.
School
7)
Were you satisfied with the printed object?
b.
Outside school: _________________
a.
Yes, it was a great print without problems
b.
Not bad, some issues
4)
How long did it take to print?
c.
I was not satisfied, very bad quality
a.
___ days
b.
___ weeks
Thank you very much to all!!
PS: If you did many 3D prints, you can post multiple answers.
Wassef…
will work slightly different from before. Sorry about breaking this, but it proved impossible to improve the selection logic with the fairly ambiguous notation that was implemented already.
Not every change is breaking though and I hope that most simple matching rules will work as before. There will be a McNeel webinar on Wednesday the 6th of November where I discuss the new selection rules (as well as path mapping syntax and relative offsets within one or more data trees). This will be a pretty hard-core webinar aimed at expert users. The event will be recorded so you can always go and watch it later. I figured I'd briefly explain the new selection rules on Ning before I release the update though.
-------------------------------------------------------------------------------
Imagine we have the following data tree, containing a bunch of textual characters:
{0;0} = [a,e,i,o,u,y] {0;1} = [ä,ë,ê,ï,î,ö,ô,õ,ü,û,ÿ,ý] {1;0} = [b,c,d,f,g,h,j,k,l,m,n,p,q,r,s,t,v,w,x,z] {1;1} = [ç,ĉ,č,ĝ,ř,š,ş,ž]
There are a total of four branches {0;0}, {0;1}, {1;0} and {1;1}. The first branch contains all the vowels that are part of the standard English alphabet. The second branch contains all non-standard vowels and branches three and four contain the standard and non-standard consonants respectively.
So what if we want to select from this tree only the standard vowels? Basically include everything in the first branch and disregard everything else. We can use the [Tree Split] component with a selection rule to achieve this:
{0;0}
This selection rule hard-codes the number zero in both tree path locations. It doesn't define an item index rule, so all items in {0;0} will be selected.
If we want all the vowels (both standard and non-standard), then we have several options:
{0;?} = select all branches that start with 0
{0;(0,1)} = select all branches that start with 0 and end in either 0 or 1
{0;(0 to 1)} = ......................................... and end in the range 0 to 1.
Conversely, selecting all standard vowels and consonants while disregarding all non-standard character can be achieved with rules as follows:
{?;0}
{(0,1);0}
{(0 to 1);0}
It is also possible to select items from each branch in addition to limiting the selection to specific branches. In this case another rule stated in square brackets needs to be appended:
{0;?}[0 to 2]
The above rule will select the first three vowels from the standard and the non-standard lists.
Basically, rules work in a very consistent way, but there are some syntax conventions you need to know. The first thing to realize is that every individual piece of data in a data-tree can be uniquely and unambiguously identified by a collection of integers. One integer describes its index within the branch and the others are used to identify the branch within the tree. As a result a rule for selection items always looks the same:
{A;B;C;...;Z}[i] where A, B, C, Z and i represent rules.
It's very similar to the Path Mapper syntax except it uses square brackets instead of parenthesis for the index (the Path Mapper will follow suit soon, but that won't be a breaking change). You always have to define the path selector rule in between curly brackets. You can supply any number of rules as long as you separate them with semi-colons.
The index rule is optional, but -when provided- it has to be encased in square brackets after the path selection rule(s).
The following rule notations are allowed:
* Any number of integers in a path
? Any single integer
6 Any specific integer
!6 Anything except a specific integer
(2,6,7) Any one of the specific integers in this group.
!(2,6,7) Anything except one of the integers in this group.
(2 to 20) Any integer in this range (including both 2 and 20).
!(2 to 20) Any integer outside this range.
(0,2,...) Any integer part of this infinite sequence. Sequences have to be at least two integers long, and every subsequent integer has to be bigger than the previous one (sorry, that may be a temporary limitation, don't know yet).
(0,2,...,48) Any integer part of this finite sequence. You can optionally provide a single sequence limit after the three dots.
!(3,5,...) Any integer not part of this infinite sequence. The sequence doesn't extend to the left, only towards the right. So this rule would select the numbers 0, 1, 2, 4, 6, 8, 10, 12 and all remaining even numbers.
!(7,10,21,...,425) Any integer not part of this finite sequence.
Furthermore, it is possible to combine two or more rules using the boolean and/or operators. If you want to select the first five items in every list of a datatree and also the items 7, 12 and 42, then the selection rule would look as follows:
{*}[(0 to 4) or (6,11,41)]
The asterisk allows you to include all branches, no matter what their paths looks like.
It is at present not possible to use the parenthesis to define rule precedence, rules are always evaluated from left to right. It is at present also not possible to use negative integers to identify items from the end of a list.
If you want to know more, join the Webinar on Wednesday!
--
David Rutten
david@mcneel.com
Seattle, WA…
Added by David Rutten at 8:57pm on November 3, 2013
d the workshop PDF from this link: http://goo.gl/bcvRNH Download event poster from this link: http://goo.gl/Q0KWCM Brief: Cairo is filled with barriers controlling people movements, suppressing them as well as detaining green and public spaces to the extent that most people have been taking these spaces for granted. Public spaces have been for a while the periphery of our daily life. We will explore in this workshop how we can manipulate and alter people’s perception and direct their attention to how these spaces are integral for city life. This exploration will be backed up by intensive technical tutorials introducing computational design and fabrication techniques and tools mainly Rhino, Grasshopper, Geco and Ecotect. Not only will this be the typical technical workshop, but rather you will also have the chance to be guided step by step on how these tools are used through out different design stages in a real world scenario. Design prototypes will be produced through 3D printing, the main workshop output will be a fabricated one to one functional model for one of the designs using our new in-house CNC machine. Tutors (check the PDF for bio): Olga Kovrikova, MArch DIA Alexandr Kalachev, MArch DIA Karim Soliman, MArch DIA Islam Ibrahim, MArch DIA Sherif Tarabishy, B.Sc. AAST Application: Application deadline 1 September 2013 ** For students (undergrad / Master), teachers and PhD proof of status is required (university ID with a date or a certificate of enrollment) to apply for the students package. Packages (choose one of the following in the application form): 1. Standard registration Course fee is 4250 EGP For Students 3500 EGP 2. Early bird registration discounted fee For Professionals 3750 EGP For Students 3000 EGP ** Early bird offer ends on 14 August 2013 3. Group registrations discounted fee (5 or more) For Students 20% off - You will have to fill out an application form here: http://goo.gl/0QxAga - You will need to submit your CV and Short Portfolio (max. 10 MB) to info@morph-d.com, email subject: “Morphing Norms Application” (we will decide if you are eligible for an early bird discount or not based on the date of your email submission) - We will confirm receiving emails from all applicants. Successful applicants will be contacted 5 days after each deadline (early bird/final) and will have to confirm participation within 3 days, if they fail to do so, places will be given to others on the waiting list. - A maximum of 30 applicants will be selected.
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t file** - ply file with just x,y,z locations. I got it from a 3d scanner. Here is how first few lines of file looks like - ply format ascii 1.0 comment VCGLIB generated element vertex 6183 property float x property float y property float z end_header -32.3271 -43.9859 11.5124 -32.0631 -43.983 11.4945 12.9266 -44.4913 28.2031 13.1701 -44.4918 28.2568 13.4138 -44.4892 28.2531 13.6581 -44.4834 28.1941 13.9012 -44.4851 28.2684 ... ... ... In case you need the data - please email me on **nisha.m234@gmail.com**. **Algorithm:** I am trying to find principal curvatures for extracting the ridges and valleys. The steps I am following is: 1. Take a point x 2. Find its k nearest neighbors. I used k from 3 to 20. 3. average the k nearest neighbors => gives (_x, _y, _z) 4. compute covariance matrix 5. Now I take eigen values and eigen vectors of this covariance matrix 6. I get u, v and n here from eigen vectors. u is a vector corresponding to largest eigen value v corresponding to 2nd largest n is 3rd smallest vector corresponding to smallest eigen value 7. Then for transforming the point(x,y,z) I compute matrix T T = [ui ] [u ] [x - _x] [vi ] = [v ] x [y - _y] [ni ] [n ] [z - _z] 8. for each i of the k nearest neighbors:<br> [ n1 ] [u1*u1 u1*v1 v1*v1] [ a ]<br> [ n2 ] = [u2*u2 u2*v2 v2*v2] [ b ] <br> [... ] [ ... ... ... ] [ c ] <br> [ nk ] [uk*uk uk*vk vk*vk]<br> Solve this for a, b and c with least squares 9. this equations will give me a,b,c 10. now I compute eigen values of matrix [a b b a ] 11. This will give me 2 eigen values. one is Kmin and another Kmax. **My Problem:** The output is no where close to finding the correct Ridges and Valleys. I am totally Stuck and frustrated. I am not sure where exactly I am getting it wrong. I think the normal's are not computed correctly. But I am not sure. I am very new to graphics programming and so this maths, normals, shaders go way above my head. Any help will be appreciated. **PLEASE PLEASE HELP!!** **Resources:** I am using Visual Studio 2010 + Eigen Library + ANN Library. **Other Options used** I tried using MeshLab. I used ball pivoting triangles remeshing in MeshLab and then applied the polkadot3d shader. If correctly identifies the ridges and valleys. But I am not able to code it. **My Function:** //the function outputs to ply file void getEigen() { int nPts; // actual number of data points ANNpointArray dataPts; // data points ANNpoint queryPt; // query point ANNidxArray nnIdx;// near neighbor indices ANNdistArray dists; // near neighbor distances ANNkd_tree* kdTree; // search structure //for k = 25 and esp = 2, seems to got few ridges queryPt = annAllocPt(dim); // allocate query point dataPts = annAllocPts(maxPts, dim); // allocate data points nnIdx = new ANNidx[k]; // allocate near neigh indices dists = new ANNdist[k]; // allocate near neighbor dists nPts = 0; // read data points ifstream dataStream; dataStream.open(inputFile, ios::in);// open data file dataIn = &dataStream; ifstream queryStream; queryStream.open("input/query.
pts", ios::in);// open data file queryIn = &queryStream; while (nPts < maxPts && readPt(*dataIn, dataPts[nPts])) nPts++; kdTree = new ANNkd_tree( // build search structure dataPts, // the data points nPts, // number of points dim); // dimension of space while (readPt(*queryIn, queryPt)) // read query points { kdTree->annkSearch( // search queryPt, // query point k, // number of near neighbors nnIdx, // nearest neighbors (returned) dists, // distance (returned) eps); // error bound double x = queryPt[0]; double y = queryPt[1]; double z = queryPt[2]; double _x = 0.0; double _y = 0.0; double _z = 0.0; #pragma region Compute covariance matrix for (int i = 0; i < k; i++) { _x += dataPts[nnIdx[i]][0]; _y += dataPts[nnIdx[i]][1]; _z += dataPts[nnIdx[i]][2]; } _x = _x/k; _y = _y/k; _z = _z/k; double A[3][3] = {0,0,0,0,0,0,0,0,0}; for (int i = 0; i < k; i++) { double X = dataPts[nnIdx[i]][0]; double Y = dataPts[nnIdx[i]][1]; double Z = dataPts[nnIdx[i]][2]; A[0][0] += (X-_x) * (X-_x); A[0][1] += (X-_x) * (Y-_y); A[0][2] += (X-_x) * (Z-_z); A[1][0] += (Y-_y) * (X-_x); A[1][1] += (Y-_y) * (Y-_y); A[1][2] += (Y-_y) * (Z-_z); A[2][0] += (Z-_z) * (X-_x); A[2][1] += (Z-_z) * (Y-_y); A[2][2] += (Z-_z) * (Z-_z); } MatrixXd C(3,3); C <<A[0][0]/k, A[0][1]/k, A[0][2]/k, A[1][0]/k, A[1][1]/k, A[1][2]/k, A[2][0]/k, A[2][1]/k, A[2][2]/k; #pragma endregion EigenSolver<MatrixXd> es(C); MatrixXd Eval = es.eigenvalues().real().asDiagonal(); MatrixXd Evec = es.eigenvectors().real(); MatrixXd u,v,n; double a = Eval.row(0).col(0).value(); double b = Eval.row(1).col(1).value(); double c = Eval.row(2).col(2).value(); #pragma region SET U V N if(a>b && a>c) { u = Evec.row(0); if(b>c) { v = Eval.row(1); n = Eval.row(2);} else { v = Eval.row(2); n = Eval.row(1);} } else if(b>a && b>c) { u = Evec.row(1); if(a>c) { v = Eval.row(0); n = Eval.row(2);} else { v = Eval.row(2); n = Eval.row(0);} } else { u = Eval.row(2); if(a>b) { v = Eval.row(0); n = Eval.row(1);} else { v = Eval.row(1); n = Eval.row(0);} } #pragma endregion MatrixXd O(3,3); O <<u, v, n; MatrixXd UV(k,3); VectorXd N(k,1); for( int i=0; i<k; i++) { double x = dataPts[nnIdx[i]][0];; double y = dataPts[nnIdx[i]][1];; double z = dataPts[nnIdx[i]][2];; MatrixXd X(3,1); X << x-_x, y-_y, z-_z; MatrixXd T = O * X; double ui = T.row(0).col(0).value(); double vi = T.row(1).col(0).value(); double ni = T.row(2).col(0).value(); UV.row(i) << ui * ui, ui * vi, vi * vi; N.row(i) << ni; } Vector3d S = UV.colPivHouseholderQr().solve(N); MatrixXd II(2,2); II << S.row(0).value(), S.row(1).value(), S.row(1).value(), S.row(2).value(); EigenSolver<MatrixXd> es2(II); MatrixXd Eval2 = es2.eigenvalues().real().asDiagonal(); MatrixXd Evec2 = es2.eigenvectors().real(); double kmin, kmax; if(Eval2.row(0).col(0).value() < Eval2.row(1).col(1).value()) { kmin = Eval2.row(0).col(0).value(); kmax = Eval2.row(1).col(1).value(); } else { kmax = Eval2.row(0).col(0).value(); kmin = Eval2.row(1).col(1).value(); } double thresh = 0.0020078; if (kmin < thresh && kmax > thresh ) cout << x << " " << y << " " << z << " " << 255 << " " << 0 << " " << 0 << endl; else cout << x << " " << y << " " << z << " " << 255 << " " << 255 << " " << 255 << endl; } delete [] nnIdx; delete [] dists; delete kdTree; annClose(); } Thanks, NISHA…