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[diderot] Diff of /branches/cuda/TODO
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Diff of /branches/cuda/TODO

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revision 1165, Mon May 9 22:02:04 2011 UTC revision 1389, Fri Jun 24 17:54:44 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  tensor fields: convolution on general tensor images (order > 1)
21    
22  ========================  ========================
23  SHORT-ISH TERM ========= (to make using Diderot less annoying to  SHORT-ISH TERM ========= (to make using Diderot less annoying to
24  ========================  program in, and slow to execute)  ========================  program in, and slow to execute)
25    
26  value-numbering optimization [DONE, but needs more testing]  Allow ".ddro" file extensions in addition to ".diderot"
27    
28  [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];
29  three scalars:  (currently only scalars & vectors).  Want to add some regression tests
30    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  
31    
32  [GLK:2] Proper handling of stabilize method  [GLK:1] Proper handling of stabilize method
33    
34  allow "*" to represent "modulate": per-component multiplication of  allow "*" to represent "modulate": per-component multiplication of
35  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 39 
39  implicit type promotion of integers to reals where reals are  implicit type promotion of integers to reals where reals are
40  required (e.g. not exponentiation "^")  required (e.g. not exponentiation "^")
41    
42  [GLK:5] Save Diderot output to nrrd, instead of "mip.txt"  [GLK:4] Save Diderot output to nrrd, instead of "mip.txt"
43    For grid of strands, save to similarly-shaped array    For grid of strands, save to similarly-shaped array
44    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
45    For ragged things (like tractography output), will need to save both    For ragged things (like tractography output), will need to save both
46      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
47      to index into complete list      to index into complete list
48    
49  [GLK:6] Use of Teem's "hest" command-line parser for getting  [GLK:5] 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  
50  *always* "inside"; with various ways of mapping the known image values  *always* "inside"; with various ways of mapping the known image values
51  to non-existant index locations.  One possible syntax emphasizes that  to non-existant index locations.  One possible syntax emphasizes that
52  there is a index mapping function that logically precedes convolution:  there is a index mapping function that logically precedes convolution:
# Line 79  Line 69 
69      rgb = real{3}      rgb = real{3}
70      rgba = real{4}      rgba = real{4}
71    
72    Revisit how images are created within the language.
73    The "load" operator should probably go away, and its strangs
74    that strings are there only as a way to refer to nrrd filenames
75    
76  ==============================  ==============================
77  MEDIUM TERM ================== (*needed* for particles)  MEDIUM TERM ================== (*needed* for particles)
78  ==============================  ==============================
# Line 87  Line 81 
81    
82  "initially" supports lists  "initially" supports lists
83    
84  "initially" supports lists of positions output from  "initially" supports lists of positions output from different
85  different initalization Diderot program  initalization Diderot program (or output from the same program;
86    e.g. using output of iso2d.diderot for one isovalue to seed the input
87    to another invocation of the same program)
88    
89  Communication between strands: they have to be able to learn each  Communication between strands: they have to be able to learn each
90  other's state (at the previous iteration).  Early version of this can  other's state (at the previous iteration).  Early version of this can
# Line 108  Line 104 
104  Allow integer exponentiation ("^2") to apply to square matrices,  Allow integer exponentiation ("^2") to apply to square matrices,
105  to represent repeated matrix multiplication  to represent repeated matrix multiplication
106    
 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.  
   
107  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
108  and when differentiation is not needed, into faster texture buffers.  and when differentiation is not needed, into faster texture buffers.
109  test/illust-vr.diderot is good example of program that uses multiple  test/illust-vr.diderot is good example of program that uses multiple
110  such 1-D fields basically as lookup-table-based function evaluation  such 1-D fields basically as lookup-table-based function evaluation
111    
 expand trace in mid to low translation  
   
112  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
113    
114  determinant ("det") for tensor[3,3]  determinant ("det") for tensor[3,3]
# Line 138  Line 128 
128  LONG TERM ==================== (make Diderot more interesting/attractive from  LONG TERM ==================== (make Diderot more interesting/attractive from
129  ==============================  a research standpoint)  ==============================  a research standpoint)
130    
131    [GLK:6] Want code-generation working for tensors of order three.
132    Order three matters for edge detection in scalar fields (to get
133    second derivatives of gradient magnitude), second derivatives
134    of vector fields (for some feature extraction), and first
135    derivatives of diffusion tensor fields.
136    
137  IL support for higher-order tensor values (matrices, etc).  IL support for higher-order tensor values (matrices, etc).
138      tensor construction [DONE]      tensor construction [DONE]
139      tensor indexing [DONE]      tensor indexing [DONE]
140      tensor slicing      tensor slicing
     verify that hessians work correctly [DONE]  
141    
142  Better handling of variables that determines the scope of a variable  Better handling of variables that determines the scope of a variable
143  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 151 
151  (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
152  conditional.  conditional.
153    
154  [GLK:8] Want: non-trivial field expressions & functions.  [GLK:7] Want: non-trivial field expressions & functions.
155  scalar fields from scalar fields F and G:  scalar fields from scalar fields F and G:
156    field#0(2)[] X = (sin(F) + 1.0)/2;    field#0(2)[] X = (sin(F) + 1.0)/2;
157    field#0(2)[] X = F*G;    field#0(2)[] X = F*G;
# Line 175  Line 170 
170  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
171  not supported (hence the indication of "field#0" for these above)  not supported (hence the indication of "field#0" for these above)
172    
173    Introduce region types (syntax region(d), where d is the dimension of the
174    region.  One useful operator would be
175            dom : field#k(d)[s] -> region(d)
176    Then the inside test could be written as
177            pos ∈ dom(F)
178    We could further extend this approach to allow geometric definitions of
179    regions.  It might also be useful to do inside tests in world space,
180    instead of image space.
181    
182  co- vs contra- index distinction  co- vs contra- index distinction
183    
184  Permit field composition:  Permit field composition:
# Line 190  Line 194 
194    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
195  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.
196    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;
197  This is especially important for things like time-varying data, or  This is especially important for things like time-varying fields
198  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
199  different from the rest, and hence must be treated separately when  must be convolved with a different kernel during probing.
200  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
201  we should notate the gradient, when we only want to differentiate with  gradient, when we only want to differentiate with respect to some
202  respect to some subset of the axes.  One ambitious idea would be:  subset of the axes.  One ambitious idea would be:
203    field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field    field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field
204    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
205    vec2 grad = ∇F([x,y]);                            // 2D gradient    vec2 grad = ∇F([x,y]);                            // 2D gradient
206    
207    Tensors of order 3 (e.g. gradients of diffusion tensor fields, or
208    hessians of vector fields) and order 4 (e.g. Hessians of diffusion
209    tensor fields).
210    
211  representation of tensor symmetry  representation of tensor symmetry
212  (have to identify the group of index permutations that are symmetries)  (have to identify the group of index permutations that are symmetries)
213    
# 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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