Home My Page Projects Code Snippets Project Openings diderot
Summary Activity Tracker Tasks SCM

SCM Repository

[diderot] Diff of /branches/fem/TODO
ViewVC logotype

Diff of /branches/fem/TODO

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

revision 1156, Sun May 8 21:20:52 2011 UTC revision 1212, Fri May 13 08:00:33 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:3] 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:4] 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 buffer
# Line 18  Line 20 
20  tensor fields: convolution on general tensor images  tensor fields: convolution on general tensor images
21    
22  ========================  ========================
23  SHORT-ISH TERM ========= (to make using Diderot less annoying/slow)  SHORT-ISH TERM ========= (to make using Diderot less annoying to
24  ========================  ========================  program in, and slow to execute)
25    
26    value-numbering optimization [DONE, but needs more testing]
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    [GLK:1] Add a clamp function, which takes three arguments; either
35    three scalars:
36      clamp(lo, hi, x)  = max(lo, min(hi, x))
37    or three vectors of the same size:
38      clamp(lo, hi, [x,y])  = [max(lo[0], min(hi[0], x)),
39                               max(lo[1], min(hi[1], y))]
40    This would be useful in many current Diderot programs.
41    One question: clamp(x, lo, hi) is the argument order used in OpenCL
42    and other places, but clamp(lo, hi, x) is much more consistent with
43    lerp(lo, hi, x), hence GLK's preference
44    
45  value-numbering optimization  [GLK:2] Proper handling of stabilize method
46    
47  proper handling of stabilize method  allow "*" to represent "modulate": per-component multiplication of
48    vectors, and vectors only (not tensors of order 2 or higher).  Once
49    sequences are implemented this should be removed: the operation is not
50    invariant WRT basis so it is not a legit vector computation.
51    
52  [GLK:2] Save Diderot output to nrrd, instead of "mip.txt"  implicit type promotion of integers to reals where reals are
53    required (e.g. not exponentiation "^")
54    
55    [GLK:5] Save Diderot output to nrrd, instead of "mip.txt"
56    For grid of strands, save to similarly-shaped array    For grid of strands, save to similarly-shaped array
57    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
58    For ragged things (like tractography output), will need to save both    For ragged things (like tractography output), will need to save both
59      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
60      to index into complete list      to index into complete list
61    
62  [GLK:3] Use of Teem's "hest" command-line parser for getting  [GLK:6] Use of Teem's "hest" command-line parser for getting
63  any input variables that are not defined in the source file  any "input" variables that are not defined in the source file.
64    
65  [GLK:4] ability to declare a field so that probe positions are  [GLK:7] ability to declare a field so that probe positions are
66  *always* "inside"; with various ways of mapping the known image values  *always* "inside"; with various ways of mapping the known image values
67  to non-existant index locations.  One possible syntax emphasizes that  to non-existant index locations.  One possible syntax emphasizes that
68  there is a index mapping function that logically precedes convolution:  there is a index mapping function that logically precedes convolution:
69    F = bspln3 ⊛ (img  clamp)    F = bspln3 ⊛ (img ◦ clamp)
70    F = bspln3 ⊛ (img ◦ repeat)    F = bspln3 ⊛ (img ◦ repeat)
71    F = bspln3 ⊛ (img ◦ mirror)    F = bspln3 ⊛ (img ◦ mirror)
72  where "◦" or "∘" is used to indicate function composition  where "◦" or "∘" is used to indicate function composition
73    
 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).  
   
74  Level of differentiability in field type should be statement about how  Level of differentiability in field type should be statement about how
75  much differentiation the program *needs*, rather than what the kernel  much differentiation the program *needs*, rather than what the kernel
76  *provides*.  The needed differentiability can be less than or equal to  *provides*.  The needed differentiability can be less than or equal to
77  the provided differentiability.  the provided differentiability.
78    
79    Use ∇⊗ etc. syntax
80        syntax [DONE]
81        typechecking
82        IL and codegen
83    
84  Add type aliases for color types  Add type aliases for color types
85      rgb = real{3}      rgb = real{3}
86      rgba = real{4}      rgba = real{4}
# Line 94  Line 111 
111    
112  support for Python interop and GUI  support for Python interop and GUI
113    
114    Allow integer exponentiation ("^2") to apply to square matrices,
115    to represent repeated matrix multiplication
116    
117  Alow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,  Alow X *= Y, X /= Y, X += Y, X -= Y to mean what they do in C,
118  provided that X*Y, X/Y, X+Y, X-Y are already supported.  provided that X*Y, X/Y, X+Y, X-Y are already supported.
119  Nearly every Diderot program would be simplified by this.  Nearly every Diderot program would be simplified by this.
# Line 142  Line 162 
162  (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
163  conditional.  conditional.
164    
165  [GLK:5] Want: non-trivial field expressions & functions:  [GLK:8] Want: non-trivial field expressions & functions.
166    scalar fields from scalar fields F and G:
167      field#0(2)[] X = (sin(F) + 1.0)/2;
168      field#0(2)[] X = F*G;
169    scalar field of vector field magnitude:
170    image(2)[2] Vimg = load(...);    image(2)[2] Vimg = load(...);
171    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
172  to get a scalar field of vector length, or  field of normalized vectors (for LIC and vector field feature extraction)
173      field#2(2)[2] F = ...
174      field#0(2)[2] V = normalize(F);
175    scalar field of gradient magnitude (for edge detection))
176    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
177    field#0(2)[] Gmag = |∇F|;    field#0(2)[] Gmag = |∇F|;
178  to get a scalar field of gradient magnitude, or  scalar field of squared gradient magnitude (simpler to differentiate):
179    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
180    field#0(2)[] Gmsq = ∇F•∇F;    field#0(2)[] Gmsq = ∇F•∇F;
181  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
182  to differentiate.  However, there is value in having these, even if  not supported (hence the indication of "field#0" for these above)
 the differentiation of them is not supported (hence the indication  
 of "field#0" for these above)  
   
 Want: ability to apply "normalize" to a field itself, e.g.  
   field#0(2)[2] V = normalize(Vimg ⊛ ctmr);  
 so that V(x) = normalize((Vimg ⊛ ctmr)(x)).  
 Having this would simplify expression of standard LIC method, and  
 would also help express other vector field expressions that arise  
 in vector field feature exraction.  
183    
184  Permit fields composition, especially for warping images by a  Introduce region types (syntax region(d), where d is the dimension of the
185  smooth field of deformation vectors  region.  One useful operator would be
186            dom : field#k(d)[s] -> region(d)
187    Then the inside test could be written as
188            pos ∈ dom(F)
189    We could further extend this approach to allow geometric definitions of
190    regions.  It might also be useful to do inside tests in world space,
191    instead of image space.
192    
193    co- vs contra- index distinction
194    
195    Permit field composition:
196    field#2(3)[3] warp = bspln3 ⊛ warpData;    field#2(3)[3] warp = bspln3 ⊛ warpData;
197    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
198    field#2(3)[] Fwarp = F ◦ warp;    field#2(3)[] Fwarp = F ◦ warp;
199  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.
200    This will be instrumental for expressing non-rigid registration
201    methods (but those will require co-vs-contra index distinction)
202    
203  Allow the convolution to be specified either as a single 1D kernel  Allow the convolution to be specified either as a single 1D kernel
204  (as we have it now):  (as we have it now):
205    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
206  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.
207    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;    field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;
208  This is especially important for things like time-varying data, or  This is especially important for things like time-varying fields
209  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
210  different from the rest.  What is very unclear is how, in such cases,  must be convolved with a different kernel during probing.
211  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
212  respect to some of the axes.  gradient, when we only want to differentiate with respect to some
213    subset of the axes.  One ambitious idea would be:
214      field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field
215      field#0(2)[] F = lambda([x,y], Ft([x,y,42.0]))     // restriction to time=42.0
216      vec2 grad = ∇F([x,y]);                             // 2D gradient
217    
218    Tensors of order 3 (e.g. gradients of diffusion tensor fields, or
219    hessians of vector fields) and order 4 (e.g. Hessians of diffusion
220    tensor fields).
221    
222  co- vs contra- index distinction  representation of tensor symmetry
   
 some indication of tensor symmetry  
223  (have to identify the group of index permutations that are symmetries)  (have to identify the group of index permutations that are symmetries)
224    
225  dot works on all tensors  dot works on all tensors
226    
227  outer works on all tensors  outer works on all tensors
228    
229    Help for debugging Diderot programs: need to be able to uniquely
230    identify strands, and for particular strands that are known to behave
231    badly, do something like printf or other logging of their computations
232    and updates.
233    
234    Permit writing dimensionally general code: Have some statement of the
235    dimension of the world "W" (or have it be learned from one particular
236    field of interest), and then able to write "vec" instead of
237    "vec2/vec3", and perhaps "tensor[W,W]" instead of
238    "tensor[2,2]/tensor[3,3]"
239    
240    Traits: all things things that have boilerplate code (especially
241    volume rendering) should be expressed in terms of the unique
242    computational core.  Different kinds of streamline/tractography
243    computation will be another example, as well as particle systems.
244    
245  Einstein summation notation  Einstein summation notation
246    
247  "tensor comprehension" (like list comprehension)  "tensor comprehension" (like list comprehension)
248    
249    Fields coming from different sources of data:
250    * triangular or tetrahedral meshes over 2D or 3D domains (of the
251      source produced by finite-element codes; these will come with their
252      own specialized kinds of reconstruction kernels, called "basis
253      functions" in this context)
254    * Large point clouds, with some radial basis function around each point,
255      which will be tuned by parameters of the point (at least one parameter
256      giving some notion of radius)
257    
258  ======================  ======================
259  BUGS =================  BUGS =================
260  ======================  ======================

Legend:
Removed from v.1156  
changed lines
  Added in v.1212

root@smlnj-gforge.cs.uchicago.edu
ViewVC Help
Powered by ViewVC 1.0.0