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[diderot] Diff of /branches/vis12/TODO
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revision 1156, Sun May 8 21:20:52 2011 UTC revision 1442, Sun Jul 10 08:09:50 2011 UTC
# Line 1  Line 1 
1  NOTE: GLK's approximate ranking of 5 most important tagged with  NOTE: GLK's approximate ranking of 8 most important tagged with
2  [GLK:1], [GLK:2], ...  [GLK:1], [GLK:2], ...
3    
4  ========================  ========================
5  SHORT TERM ============= (*needed* for streamlines & tractography)  SHORT TERM ============= (*needed* for streamlines & tractography)
6  ========================  ========================
7    
8  [GLK:1] 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  [GLK:1] evals & evecs for symmetric tensor[3,3] (requires sequences)  
14    [GLK:3] evals & evecs for symmetric tensor[2,2] and
15    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/slow)  SHORT-ISH TERM ========= (to make using Diderot less annoying to
26  ========================  ========================  program in, and slow to execute)
27    
28    Allow ".ddro" file extensions in addition to ".diderot"
29    
30    Be able to output values of type tensor[2,2] and tensor[3,3];
31    (currently only scalars & vectors).  Want to add some regression tests
32    based on this and currently can't
33    
34  value-numbering optimization  [GLK:1] Proper handling of stabilize method
35    
36  proper handling of stabilize method  Convolution on general tensor images (order > 2)
37    
38  [GLK:2] Save Diderot output to nrrd, instead of "mip.txt"  allow "*" to represent "modulate": per-component multiplication of
39    vectors, and vectors only (not tensors of order 2 or higher).  Once
40    sequences are implemented this should be removed: the operation is not
41    invariant WRT basis so it is not a legit vector computation.
42    
43    implicit type promotion of integers to reals where reals are
44    required (e.g. not exponentiation "^")
45    
46    [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: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  
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:
57    F = bspln3 ⊛ (img  clamp)    F = bspln3 ⊛ (img ◦ clamp)
58    F = bspln3 ⊛ (img ◦ repeat)    F = bspln3 ⊛ (img ◦ repeat)
59    F = bspln3 ⊛ (img ◦ mirror)    F = bspln3 ⊛ (img ◦ mirror)
60  where "◦" or "∘" is used to indicate function composition  where "◦" or "∘" is used to indicate function composition
61    
 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).  
   
62  Level of differentiability in field type should be statement about how  Level of differentiability in field type should be statement about how
63  much differentiation the program *needs*, rather than what the kernel  much differentiation the program *needs*, rather than what the kernel
64  *provides*.  The needed differentiability can be less than or equal to  *provides*.  The needed differentiability can be less than or equal to
65  the provided differentiability.  the provided differentiability.
66    
67    Use ∇⊗ etc. syntax
68        syntax [DONE]
69        typechecking
70        IL and codegen
71    
72  Add type aliases for color types  Add type aliases for color types
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
113    
114  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,
115  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.  
116    
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 128  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 142  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:5] Want: non-trivial field expressions & functions:  [GLK:7] Want: non-trivial field expressions & functions.
159    scalar fields from scalar fields F and G:
160      field#0(2)[] X = (sin(F) + 1.0)/2;
161      field#0(2)[] X = F*G;
162    scalar field of vector field magnitude:
163    image(2)[2] Vimg = load(...);    image(2)[2] Vimg = load(...);
164    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
165  to get a scalar field of vector length, or  field of normalized vectors (for LIC and vector field feature extraction)
166      field#2(2)[2] F = ...
167      field#0(2)[2] V = normalize(F);
168    scalar field of gradient magnitude (for edge detection))
169    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
170    field#0(2)[] Gmag = |∇F|;    field#0(2)[] Gmag = |∇F|;
171  to get a scalar field of gradient magnitude, or  scalar field of squared gradient magnitude (simpler to differentiate):
172    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
173    field#0(2)[] Gmsq = ∇F•∇F;    field#0(2)[] Gmsq = ∇F•∇F;
174  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
175  to differentiate.  However, there is value in having these, even if  not supported (hence the indication of "field#0" for these above)
176  the differentiation of them is not supported (hence the indication  
177  of "field#0" for these above)  Introduce region types (syntax region(d), where d is the dimension of the
178    region.  One useful operator would be
179  Want: ability to apply "normalize" to a field itself, e.g.          dom : field#k(d)[s] -> region(d)
180    field#0(2)[2] V = normalize(Vimg ⊛ ctmr);  Then the inside test could be written as
181  so that V(x) = normalize((Vimg ⊛ ctmr)(x)).          pos ∈ dom(F)
182  Having this would simplify expression of standard LIC method, and  We could further extend this approach to allow geometric definitions of
183  would also help express other vector field expressions that arise  regions.  It might also be useful to do inside tests in world space,
184  in vector field feature exraction.  instead of image space.
185    
186  Permit fields composition, especially for warping images by a  co- vs contra- index distinction
187  smooth field of deformation vectors  
188    Permit field composition:
189    field#2(3)[3] warp = bspln3 ⊛ warpData;    field#2(3)[3] warp = bspln3 ⊛ warpData;
190    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
191    field#2(3)[] Fwarp = F ◦ warp;    field#2(3)[] Fwarp = F ◦ warp;
192  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.
193    This will be instrumental for expressing non-rigid registration
194    methods (but those will require co-vs-contra index distinction)
195    
196  Allow the convolution to be specified either as a single 1D kernel  Allow the convolution to be specified either as a single 1D kernel
197  (as we have it now):  (as we have it now):
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.  What is very unclear is how, in such cases,  must be convolved with a different kernel during probing.
204  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
205  respect to some of the axes.  gradient, when we only want to differentiate with respect to some
206    subset of the axes.  One ambitious idea would be:
207  co- vs contra- index distinction    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
209      vec2 grad = ∇F([x,y]);                             // 2D gradient
210    
211  some indication 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    
214  dot works on all tensors  dot works on all tensors
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 203  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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