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[diderot] Diff of /branches/cuda/TODO
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revision 1165, Mon May 9 22:02:04 2011 UTC revision 1442, Sun Jul 10 08:09:50 2011 UTC
# Line 5  Line 5 
5  SHORT TERM ============= (*needed* for streamlines & tractography)  SHORT TERM ============= (*needed* for streamlines & tractography)
6  ========================  ========================
7    
8  [GLK:3] Add sequence types (needed for evals & evecs)  [GLK:2] Add sequence types (needed for evals & evecs)
9      syntax      syntax
10          types: ty '{' INT '}'          types: ty '{' INT '}'
11          value construction: '{' e1 ',' … ',' en '}'          value construction: '{' e1 ',' … ',' en '}'
12          indexing: e '{' e '}'          indexing: e '{' e '}'
13    
14  [GLK:4] evals & evecs for symmetric tensor[2,2] and  [GLK:3] evals & evecs for symmetric tensor[2,2] and
15  tensor[3,3] (requires sequences)  tensor[3,3] (requires sequences)
16    
17  ability to emit/track/record variables into dynamically re-sized  ability to emit/track/record variables into dynamically re-sized
18  runtime buffer  runtime output buffer
19    
20  tensor fields: convolution on general tensor images  [GLK:4] tensor fields from tensor images: Initially need at least
21    convolution on tensor[2,2] and tensor[3,3] (the same component-wise
22    convolution as for vectors).
23    
24  ========================  ========================
25  SHORT-ISH TERM ========= (to make using Diderot less annoying to  SHORT-ISH TERM ========= (to make using Diderot less annoying to
26  ========================  program in, and slow to execute)  ========================  program in, and slow to execute)
27    
28  value-numbering optimization [DONE, but needs more testing]  Allow ".ddro" file extensions in addition to ".diderot"
29    
30  [GLK:1] Add a clamp function, which takes three arguments; either  Be able to output values of type tensor[2,2] and tensor[3,3];
31  three scalars:  (currently only scalars & vectors).  Want to add some regression tests
32    clamp(lo, hi, x)  = max(lo, min(hi, x))  based on this and currently can't
 or three vectors of the same size:  
   clamp(lo, hi, [x,y])  = [max(lo[0], min(hi[0], x)),  
                            max(lo[1], min(hi[1], y))]  
 This would be useful in many current Diderot programs.  
 One question: clamp(x, lo, hi) is the argument order used in OpenCL  
 and other places, but clamp(lo, hi, x) is much more consistent with  
 lerp(lo, hi, x), hence GLK's preference  
33    
34  [GLK:2] Proper handling of stabilize method  [GLK:1] Proper handling of stabilize method
35    
36    Convolution on general tensor images (order > 2)
37    
38  allow "*" to represent "modulate": per-component multiplication of  allow "*" to represent "modulate": per-component multiplication of
39  vectors, and vectors only (not tensors of order 2 or higher).  Once  vectors, and vectors only (not tensors of order 2 or higher).  Once
# Line 46  Line 43 
43  implicit type promotion of integers to reals where reals are  implicit type promotion of integers to reals where reals are
44  required (e.g. not exponentiation "^")  required (e.g. not exponentiation "^")
45    
46  [GLK:5] Save Diderot output to nrrd, instead of "mip.txt"  [Nick working on this] Save Diderot output to nrrd, instead of "mip.txt"
47    For grid of strands, save to similarly-shaped array    For grid of strands, save to similarly-shaped array
48    For list of strands, save to long 1-D (or 2-D for non-scalar output) list    For list of strands, save to long 1-D (or 2-D for non-scalar output) list
49    For ragged things (like tractography output), will need to save both    For ragged things (like tractography output), will need to save both
50      complete list of values, as well as list of start indices and lengths      complete list of values, as well as list of start indices and lengths
51      to index into complete list      to index into complete list
52    
53  [GLK:6] Use of Teem's "hest" command-line parser for getting  [GLK:6] ability to declare a field so that probe positions are
 any input variables that are not defined in the source file  
   
 [GLK:7] ability to declare a field so that probe positions are  
54  *always* "inside"; with various ways of mapping the known image values  *always* "inside"; with various ways of mapping the known image values
55  to non-existant index locations.  One possible syntax emphasizes that  to non-existant index locations.  One possible syntax emphasizes that
56  there is a index mapping function that logically precedes convolution:  there is a index mapping function that logically precedes convolution:
# Line 79  Line 73 
73      rgb = real{3}      rgb = real{3}
74      rgba = real{4}      rgba = real{4}
75    
76    Revisit how images are created within the language.
77    The "load" operator should probably go away, and its strangs
78    that strings are there only as a way to refer to nrrd filenames
79    
80  ==============================  ==============================
81  MEDIUM TERM ================== (*needed* for particles)  MEDIUM TERM ================== (*needed* for particles)
82  ==============================  ==============================
83    
84  run-time birth of strands  [Lamont working on this] run-time birth of strands
85    
86  "initially" supports lists  "initially" supports lists
87    
88  "initially" supports lists of positions output from  "initially" supports lists of positions output from different
89  different initalization Diderot program  initalization Diderot program (or output from the same program;
90    e.g. using output of iso2d.diderot for one isovalue to seed the input
91  Communication between strands: they have to be able to learn each  to another invocation of the same program)
92  other's state (at the previous iteration).  Early version of this can  
93  have the network of neighbors be completely static (for running one  [Lamont working on this] Communication between strands: they have to
94  strand/pixel image computations).  Later version with strands moving  be able to learn each other's state (at the previous iteration).
95  through the domain will require some spatial data structure to  Early version of this can have the network of neighbors be completely
96  optimize discovery of neighbors.  static (for running one strand/pixel image computations).  Later
97    version with strands moving through the domain will require some
98    spatial data structure to optimize discovery of neighbors.
99    
100  ============================  ============================
101  MEDIUM-ISH TERM ============ (to make Diderot more useful/effective)  MEDIUM-ISH TERM ============ (to make Diderot more useful/effective)
102  ============================  ============================
103    
104    [GLK:5] Want code-generation working for tensors of order three.
105    Order three matters for edge detection in scalar fields (to get
106    second derivatives of gradient magnitude), second derivatives
107    of vector fields (for some feature extraction), and first
108    derivatives of diffusion tensor fields.
109    
110  Python/ctypes interface to run-time  Python/ctypes interface to run-time
111    
112  support for Python interop and GUI  support for Python interop and GUI
# Line 108  Line 114 
114  Allow integer exponentiation ("^2") to apply to square matrices,  Allow integer exponentiation ("^2") to apply to square matrices,
115  to represent repeated matrix multiplication  to represent repeated matrix multiplication
116    
 Alow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,  
 provided that X*Y, X/Y, X+Y, X-Y are already supported.  
 Nearly every Diderot program would be simplified by this.  
   
117  Put small 1-D and 2-D fields, when reconstructed specifically by tent  Put small 1-D and 2-D fields, when reconstructed specifically by tent
118  and when differentiation is not needed, into faster texture buffers.  and when differentiation is not needed, into faster texture buffers.
119  test/illust-vr.diderot is good example of program that uses multiple  test/illust-vr.diderot is good example of program that uses multiple
120  such 1-D fields basically as lookup-table-based function evaluation  such 1-D fields basically as lookup-table-based function evaluation
121    
 expand trace in mid to low translation  
   
122  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
123    
124  determinant ("det") for tensor[3,3]  determinant ("det") for tensor[3,3]
# Line 142  Line 142 
142      tensor construction [DONE]      tensor construction [DONE]
143      tensor indexing [DONE]      tensor indexing [DONE]
144      tensor slicing      tensor slicing
     verify that hessians work correctly [DONE]  
145    
146  Better handling of variables that determines the scope of a variable  Better handling of variables that determines the scope of a variable
147  based on its actual use, instead of where the user defined it.  So,  based on its actual use, instead of where the user defined it.  So,
# Line 156  Line 155 
155  (but we should only duplicate over the live-range of the result of the  (but we should only duplicate over the live-range of the result of the
156  conditional.  conditional.
157    
158  [GLK:8] Want: non-trivial field expressions & functions.  [GLK:7] Want: non-trivial field expressions & functions.
159  scalar fields from scalar fields F and G:  scalar fields from scalar fields F and G:
160    field#0(2)[] X = (sin(F) + 1.0)/2;    field#0(2)[] X = (sin(F) + 1.0)/2;
161    field#0(2)[] X = F*G;    field#0(2)[] X = F*G;
# Line 175  Line 174 
174  There is value in having these, even if the differentiation of them is  There is value in having these, even if the differentiation of them is
175  not supported (hence the indication of "field#0" for these above)  not supported (hence the indication of "field#0" for these above)
176    
177    Introduce region types (syntax region(d), where d is the dimension of the
178    region.  One useful operator would be
179            dom : field#k(d)[s] -> region(d)
180    Then the inside test could be written as
181            pos ∈ dom(F)
182    We could further extend this approach to allow geometric definitions of
183    regions.  It might also be useful to do inside tests in world space,
184    instead of image space.
185    
186  co- vs contra- index distinction  co- vs contra- index distinction
187    
188  Permit field composition:  Permit field composition:
# Line 190  Line 198 
198    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
199  or, as a tensor product of kernels, one for each axis, e.g.  or, as a tensor product of kernels, one for each axis, e.g.
200    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;
201  This is especially important for things like time-varying data, or  This is especially important for things like time-varying fields
202  other multi-dimensional fields where one axis of the domain is very  and the use of scale-space in field visualization: one axis of the
203  different from the rest, and hence must be treated separately when  must be convolved with a different kernel during probing.
204  it comes to convolution.  What is very unclear is how, in such cases,  What is very unclear is how, in such cases, we should notate the
205  we should notate the gradient, when we only want to differentiate with  gradient, when we only want to differentiate with respect to some
206  respect to some subset of the axes.  One ambitious idea would be:  subset of the axes.  One ambitious idea would be:
207    field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field    field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field
208    field#0(2)[] F = lambda([x,y], Ft([x,y,42.0]))    // restriction to time=42.0    field#0(2)[] F = lambda([x,y], Ft([x,y,42.0]))    // restriction to time=42.0
209    vec2 grad = ∇F([x,y]);                            // 2D gradient    vec2 grad = ∇F([x,y]);                            // 2D gradient
# Line 207  Line 215 
215    
216  outer works on all tensors  outer works on all tensors
217    
218    Help for debugging Diderot programs: need to be able to uniquely
219    identify strands, and for particular strands that are known to behave
220    badly, do something like printf or other logging of their computations
221    and updates.
222    
223    Permit writing dimensionally general code: Have some statement of the
224    dimension of the world "W" (or have it be learned from one particular
225    field of interest), and then able to write "vec" instead of
226    "vec2/vec3", and perhaps "tensor[W,W]" instead of
227    "tensor[2,2]/tensor[3,3]"
228    
229    Traits: all things things that have boilerplate code (especially
230    volume rendering) should be expressed in terms of the unique
231    computational core.  Different kinds of streamline/tractography
232    computation will be another example, as well as particle systems.
233    
234  Einstein summation notation  Einstein summation notation
235    
236  "tensor comprehension" (like list comprehension)  "tensor comprehension" (like list comprehension)
237    
238    Fields coming from different sources of data:
239    * triangular or tetrahedral meshes over 2D or 3D domains (of the
240      source produced by finite-element codes; these will come with their
241      own specialized kinds of reconstruction kernels, called "basis
242      functions" in this context)
243    * Large point clouds, with some radial basis function around each point,
244      which will be tuned by parameters of the point (at least one parameter
245      giving some notion of radius)
246    
247  ======================  ======================
248  BUGS =================  BUGS =================
249  ======================  ======================
# Line 220  Line 253 
253  //  uncaught exception Size [size]  //  uncaught exception Size [size]
254  //    raised at c-target/c-target.sml:47.15-47.19  //    raised at c-target/c-target.sml:47.15-47.19
255  //field#4(3)[] F = img ⊛ bspln5;  //field#4(3)[] F = img ⊛ bspln5;
256    

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