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[diderot] Diff of /branches/cuda/TODO
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revision 1156, Sun May 8 21:20:52 2011 UTC revision 1445, Mon Jul 11 16:21:47 2011 UTC
# Line 1  Line 1 
1  NOTE: GLK's approximate ranking of 5 most important tagged with  THIS TODO HAS BEEN MOVED TO THE DIDEROT WIKI.  PLEASE USE THAT ONE.
2    
3    NOTE: GLK's approximate ranking of 8 most important tagged with
4  [GLK:1], [GLK:2], ...  [GLK:1], [GLK:2], ...
5    
6  ========================  ========================
7  SHORT TERM ============= (*needed* for streamlines & tractography)  SHORT TERM ============= (*needed* for streamlines & tractography)
8  ========================  ========================
9    
10  [GLK:1] Add sequence types (needed for evals & evecs)  [GLK:2] Add sequence types (needed for evals & evecs)
11      syntax      syntax
12          types: ty '{' INT '}'          types: ty '{' INT '}'
13          value construction: '{' e1 ',' … ',' en '}'          value construction: '{' e1 ',' … ',' en '}'
14          indexing: e '{' e '}'          indexing: e '{' e '}'
15  [GLK:1] evals & evecs for symmetric tensor[3,3] (requires sequences)  
16    [GLK:3] evals & evecs for symmetric tensor[2,2] and
17    tensor[3,3] (requires sequences)
18    
19  ability to emit/track/record variables into dynamically re-sized  ability to emit/track/record variables into dynamically re-sized
20  runtime buffer  runtime output buffer
21    
22  tensor fields: convolution on general tensor images  [GLK:4] tensor fields from tensor images: Initially need at least
23    convolution on tensor[2,2] and tensor[3,3] (the same component-wise
24    convolution as for vectors).
25    
26  ========================  ========================
27  SHORT-ISH TERM ========= (to make using Diderot less annoying/slow)  SHORT-ISH TERM ========= (to make using Diderot less annoying to
28  ========================  ========================  program in, and slow to execute)
29    
30    Allow ".ddro" file extensions in addition to ".diderot"
31    
32  value-numbering optimization  Be able to output values of type tensor[2,2] and tensor[3,3];
33    (currently only scalars & vectors).  Want to add some regression tests
34    based on this and currently can't
35    
36  proper handling of stabilize method  [GLK:1] Proper handling of stabilize method
37    
38  [GLK:2] Save Diderot output to nrrd, instead of "mip.txt"  Convolution on general tensor images (order > 2)
39    
40    allow "*" to represent "modulate": per-component multiplication of
41    vectors, and vectors only (not tensors of order 2 or higher).  Once
42    sequences are implemented this should be removed: the operation is not
43    invariant WRT basis so it is not a legit vector computation.
44    
45    implicit type promotion of integers to reals where reals are
46    required (e.g. not exponentiation "^")
47    
48    [Nick working on this] Save Diderot output to nrrd, instead of "mip.txt"
49    For grid of strands, save to similarly-shaped array    For grid of strands, save to similarly-shaped array
50    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
51    For ragged things (like tractography output), will need to save both    For ragged things (like tractography output), will need to save both
52      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
53      to index into complete list      to index into complete list
54    
55  [GLK:3] 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:4] ability to declare a field so that probe positions are  
56  *always* "inside"; with various ways of mapping the known image values  *always* "inside"; with various ways of mapping the known image values
57  to non-existant index locations.  One possible syntax emphasizes that  to non-existant index locations.  One possible syntax emphasizes that
58  there is a index mapping function that logically precedes convolution:  there is a index mapping function that logically precedes convolution:
59    F = bspln3 ⊛ (img  clamp)    F = bspln3 ⊛ (img ◦ clamp)
60    F = bspln3 ⊛ (img ◦ repeat)    F = bspln3 ⊛ (img ◦ repeat)
61    F = bspln3 ⊛ (img ◦ mirror)    F = bspln3 ⊛ (img ◦ mirror)
62  where "◦" or "∘" is used to indicate function composition  where "◦" or "∘" is used to indicate function composition
63    
 Use ∇⊗ etc. syntax  
     syntax [DONE]  
     typechecking  
     IL and codegen  
   
 Add a clamp function, which takes three arguments; either three scalars:  
   clamp(x, minval, maxval)  = max(minval, min(maxval, x))  
 or three vectors of the same size:  
   clamp([x,y], minvec, maxvec)  = [max(minvec[0], min(maxvec[0], x)),  
                                    max(minvec[1], min(maxvec[1], y))]  
 This would be useful in many current Diderot programs.  
 One question: clamp(x, minval, maxval) is the argument order  
 used in OpenCL and other places, but clamp(minval, maxval, x)  
 would be more consistent with lerp(minout, maxout, x).  
   
64  Level of differentiability in field type should be statement about how  Level of differentiability in field type should be statement about how
65  much differentiation the program *needs*, rather than what the kernel  much differentiation the program *needs*, rather than what the kernel
66  *provides*.  The needed differentiability can be less than or equal to  *provides*.  The needed differentiability can be less than or equal to
67  the provided differentiability.  the provided differentiability.
68    
69    Use ∇⊗ etc. syntax
70        syntax [DONE]
71        typechecking
72        IL and codegen
73    
74  Add type aliases for color types  Add type aliases for color types
75      rgb = real{3}      rgb = real{3}
76      rgba = real{4}      rgba = real{4}
77    
78    Revisit how images are created within the language.
79    The "load" operator should probably go away, and its strangs
80    that strings are there only as a way to refer to nrrd filenames
81    
82  ==============================  ==============================
83  MEDIUM TERM ================== (*needed* for particles)  MEDIUM TERM ================== (*needed* for particles)
84  ==============================  ==============================
85    
86  run-time birth of strands  [Lamont working on this] run-time birth of strands
87    
88  "initially" supports lists  "initially" supports lists
89    
90  "initially" supports lists of positions output from  "initially" supports lists of positions output from different
91  different initalization Diderot program  initalization Diderot program (or output from the same program;
92    e.g. using output of iso2d.diderot for one isovalue to seed the input
93  Communication between strands: they have to be able to learn each  to another invocation of the same program)
94  other's state (at the previous iteration).  Early version of this can  
95  have the network of neighbors be completely static (for running one  [Lamont working on this] Communication between strands: they have to
96  strand/pixel image computations).  Later version with strands moving  be able to learn each other's state (at the previous iteration).
97  through the domain will require some spatial data structure to  Early version of this can have the network of neighbors be completely
98  optimize discovery of neighbors.  static (for running one strand/pixel image computations).  Later
99    version with strands moving through the domain will require some
100    spatial data structure to optimize discovery of neighbors.
101    
102  ============================  ============================
103  MEDIUM-ISH TERM ============ (to make Diderot more useful/effective)  MEDIUM-ISH TERM ============ (to make Diderot more useful/effective)
104  ============================  ============================
105    
106    [GLK:5] Want code-generation working for tensors of order three.
107    Order three matters for edge detection in scalar fields (to get
108    second derivatives of gradient magnitude), second derivatives
109    of vector fields (for some feature extraction), and first
110    derivatives of diffusion tensor fields.
111    
112  Python/ctypes interface to run-time  Python/ctypes interface to run-time
113    
114  support for Python interop and GUI  support for Python interop and GUI
115    
116  Alow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,  Allow integer exponentiation ("^2") to apply to square matrices,
117  provided that X*Y, X/Y, X+Y, X-Y are already supported.  to represent repeated matrix multiplication
 Nearly every Diderot program would be simplified by this.  
118    
119  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
120  and when differentiation is not needed, into faster texture buffers.  and when differentiation is not needed, into faster texture buffers.
121  test/illust-vr.diderot is good example of program that uses multiple  test/illust-vr.diderot is good example of program that uses multiple
122  such 1-D fields basically as lookup-table-based function evaluation  such 1-D fields basically as lookup-table-based function evaluation
123    
 expand trace in mid to low translation  
   
124  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
125    
126  determinant ("det") for tensor[3,3]  determinant ("det") for tensor[3,3]
# Line 128  Line 144 
144      tensor construction [DONE]      tensor construction [DONE]
145      tensor indexing [DONE]      tensor indexing [DONE]
146      tensor slicing      tensor slicing
     verify that hessians work correctly [DONE]  
147    
148  Better handling of variables that determines the scope of a variable  Better handling of variables that determines the scope of a variable
149  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 142  Line 157 
157  (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
158  conditional.  conditional.
159    
160  [GLK:5] Want: non-trivial field expressions & functions:  [GLK:7] Want: non-trivial field expressions & functions.
161    scalar fields from scalar fields F and G:
162      field#0(2)[] X = (sin(F) + 1.0)/2;
163      field#0(2)[] X = F*G;
164    scalar field of vector field magnitude:
165    image(2)[2] Vimg = load(...);    image(2)[2] Vimg = load(...);
166    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
167  to get a scalar field of vector length, or  field of normalized vectors (for LIC and vector field feature extraction)
168      field#2(2)[2] F = ...
169      field#0(2)[2] V = normalize(F);
170    scalar field of gradient magnitude (for edge detection))
171    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
172    field#0(2)[] Gmag = |∇F|;    field#0(2)[] Gmag = |∇F|;
173  to get a scalar field of gradient magnitude, or  scalar field of squared gradient magnitude (simpler to differentiate):
174    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
175    field#0(2)[] Gmsq = ∇F•∇F;    field#0(2)[] Gmsq = ∇F•∇F;
176  to get a scalar field of squared gradient magnitude, which is simpler  There is value in having these, even if the differentiation of them is
177  to differentiate.  However, there is value in having these, even if  not supported (hence the indication of "field#0" for these above)
178  the differentiation of them is not supported (hence the indication  
179  of "field#0" for these above)  Introduce region types (syntax region(d), where d is the dimension of the
180    region.  One useful operator would be
181  Want: ability to apply "normalize" to a field itself, e.g.          dom : field#k(d)[s] -> region(d)
182    field#0(2)[2] V = normalize(Vimg ⊛ ctmr);  Then the inside test could be written as
183  so that V(x) = normalize((Vimg ⊛ ctmr)(x)).          pos ∈ dom(F)
184  Having this would simplify expression of standard LIC method, and  We could further extend this approach to allow geometric definitions of
185  would also help express other vector field expressions that arise  regions.  It might also be useful to do inside tests in world space,
186  in vector field feature exraction.  instead of image space.
187    
188  Permit fields composition, especially for warping images by a  co- vs contra- index distinction
189  smooth field of deformation vectors  
190    Permit field composition:
191    field#2(3)[3] warp = bspln3 ⊛ warpData;    field#2(3)[3] warp = bspln3 ⊛ warpData;
192    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
193    field#2(3)[] Fwarp = F ◦ warp;    field#2(3)[] Fwarp = F ◦ warp;
194  So Fwarp(x) = F(warp(X)).  Chain rule can be used for differentation  So Fwarp(x) = F(warp(X)).  Chain rule can be used for differentation.
195    This will be instrumental for expressing non-rigid registration
196    methods (but those will require co-vs-contra index distinction)
197    
198  Allow the convolution to be specified either as a single 1D kernel  Allow the convolution to be specified either as a single 1D kernel
199  (as we have it now):  (as we have it now):
200    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
201  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.
202    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;
203  This is especially important for things like time-varying data, or  This is especially important for things like time-varying fields
204  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
205  different from the rest.  What is very unclear is how, in such cases,  must be convolved with a different kernel during probing.
206  we should notate the gradient, when we only want to differentiate with  What is very unclear is how, in such cases, we should notate the
207  respect to some of the axes.  gradient, when we only want to differentiate with respect to some
208    subset of the axes.  One ambitious idea would be:
209  co- vs contra- index distinction    field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field
210      field#0(2)[] F = lambda([x,y], Ft([x,y,42.0]))     // restriction to time=42.0
211      vec2 grad = ∇F([x,y]);                             // 2D gradient
212    
213  some indication of tensor symmetry  representation of tensor symmetry
214  (have to identify the group of index permutations that are symmetries)  (have to identify the group of index permutations that are symmetries)
215    
216  dot works on all tensors  dot works on all tensors
217    
218  outer works on all tensors  outer works on all tensors
219    
220    Help for debugging Diderot programs: need to be able to uniquely
221    identify strands, and for particular strands that are known to behave
222    badly, do something like printf or other logging of their computations
223    and updates.
224    
225    Permit writing dimensionally general code: Have some statement of the
226    dimension of the world "W" (or have it be learned from one particular
227    field of interest), and then able to write "vec" instead of
228    "vec2/vec3", and perhaps "tensor[W,W]" instead of
229    "tensor[2,2]/tensor[3,3]"
230    
231    Traits: all things things that have boilerplate code (especially
232    volume rendering) should be expressed in terms of the unique
233    computational core.  Different kinds of streamline/tractography
234    computation will be another example, as well as particle systems.
235    
236  Einstein summation notation  Einstein summation notation
237    
238  "tensor comprehension" (like list comprehension)  "tensor comprehension" (like list comprehension)
239    
240    Fields coming from different sources of data:
241    * triangular or tetrahedral meshes over 2D or 3D domains (of the
242      source produced by finite-element codes; these will come with their
243      own specialized kinds of reconstruction kernels, called "basis
244      functions" in this context)
245    * Large point clouds, with some radial basis function around each point,
246      which will be tuned by parameters of the point (at least one parameter
247      giving some notion of radius)
248    
249  ======================  ======================
250  BUGS =================  BUGS =================
251  ======================  ======================
# Line 203  Line 255 
255  //  uncaught exception Size [size]  //  uncaught exception Size [size]
256  //    raised at c-target/c-target.sml:47.15-47.19  //    raised at c-target/c-target.sml:47.15-47.19
257  //field#4(3)[] F = img ⊛ bspln5;  //field#4(3)[] F = img ⊛ bspln5;
258    

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