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

# Diff of /branches/lamont/TODO

revision 1156, Sun May 8 21:20:52 2011 UTC revision 1388, Fri Jun 24 14:45:33 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)  Remove CL from compiler [DONE]
9
10    [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 buffer
21
22  tensor fields: convolution on general tensor images  tensor fields: convolution on general tensor images (order > 1)
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    value-numbering optimization [DONE]
29
30    Allow ".ddro" file extensions in addition to ".diderot"
31
32    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    [GLK:1] Proper handling of stabilize method
37
38  value-numbering optimization  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  proper handling of stabilize method  implicit type promotion of integers to reals where reals are
44    required (e.g. not exponentiation "^")
45
46  [GLK:2] Save Diderot output to nrrd, instead of "mip.txt"  [GLK:4] 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:5] Use of Teem's "hest" command-line parser for getting
54  any input variables that are not defined in the source file  any "input" variables that are not defined in the source file. [DONE]
55
56  [GLK:4] ability to declare a field so that probe positions are  [GLK:6] ability to declare a field so that probe positions are
57  *always* "inside"; with various ways of mapping the known image values  *always* "inside"; with various ways of mapping the known image values
58  to non-existant index locations.  One possible syntax emphasizes that  to non-existant index locations.  One possible syntax emphasizes that
59  there is a index mapping function that logically precedes convolution:  there is a index mapping function that logically precedes convolution:
60    F = bspln3 ⊛ (img  clamp)    F = bspln3 ⊛ (img ◦ clamp)
61    F = bspln3 ⊛ (img ◦ repeat)    F = bspln3 ⊛ (img ◦ repeat)
62    F = bspln3 ⊛ (img ◦ mirror)    F = bspln3 ⊛ (img ◦ mirror)
63  where "◦" or "∘" is used to indicate function composition  where "◦" or "∘" is used to indicate function composition
64
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).

65  Level of differentiability in field type should be statement about how  Level of differentiability in field type should be statement about how
66  much differentiation the program *needs*, rather than what the kernel  much differentiation the program *needs*, rather than what the kernel
67  *provides*.  The needed differentiability can be less than or equal to  *provides*.  The needed differentiability can be less than or equal to
68  the provided differentiability.  the provided differentiability.
69
70    Use ∇⊗ etc. syntax
71        syntax [DONE]
72        typechecking
73        IL and codegen
74
75  Add type aliases for color types  Add type aliases for color types
76      rgb = real{3}      rgb = real{3}
77      rgba = real{4}      rgba = real{4}
# Line 76  Line 84
84
85  "initially" supports lists  "initially" supports lists
86
87  "initially" supports lists of positions output from  "initially" supports lists of positions output from different
88  different initalization Diderot program  initalization Diderot program (or output from the same program;
89    e.g. using output of iso2d.diderot for one isovalue to seed the input
90    to another invocation of the same program)
91
92  Communication between strands: they have to be able to learn each  Communication between strands: they have to be able to learn each
93  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 94  Line 104
104
105  support for Python interop and GUI  support for Python interop and GUI
106
107  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,
108  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.
109
110  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
111  and when differentiation is not needed, into faster texture buffers.  and when differentiation is not needed, into faster texture buffers.
112  test/illust-vr.diderot is good example of program that uses multiple  test/illust-vr.diderot is good example of program that uses multiple
113  such 1-D fields basically as lookup-table-based function evaluation  such 1-D fields basically as lookup-table-based function evaluation
114
115  expand trace in mid to low translation  expand trace in mid to low translation [DONE]
116
117  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]  extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
118
# Line 142  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:5] Want: non-trivial field expressions & functions:  [GLK:7] Want: non-trivial field expressions & functions.
155    scalar fields from scalar fields F and G:
156      field#0(2)[] X = (sin(F) + 1.0)/2;
157      field#0(2)[] X = F*G;
158    scalar field of vector field magnitude:
159    image(2)[2] Vimg = load(...);    image(2)[2] Vimg = load(...);
160    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;    field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
161  to get a scalar field of vector length, or  field of normalized vectors (for LIC and vector field feature extraction)
162      field#2(2)[2] F = ...
163      field#0(2)[2] V = normalize(F);
164    scalar field of gradient magnitude (for edge detection))
165    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
166    field#0(2)[] Gmag = |∇F|;    field#0(2)[] Gmag = |∇F|;
167  to get a scalar field of gradient magnitude, or  scalar field of squared gradient magnitude (simpler to differentiate):
168    field#2(2)[] F = Fimg ⊛ bspln3;    field#2(2)[] F = Fimg ⊛ bspln3;
169    field#0(2)[] Gmsq = ∇F•∇F;    field#0(2)[] Gmsq = ∇F•∇F;
170  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
171  to differentiate.  However, there is value in having these, even if  not supported (hence the indication of "field#0" for these above)
172  the differentiation of them is not supported (hence the indication
173  of "field#0" for these above)  Introduce region types (syntax region(d), where d is the dimension of the
174    region.  One useful operator would be
175  Want: ability to apply "normalize" to a field itself, e.g.          dom : field#k(d)[s] -> region(d)
176    field#0(2)[2] V = normalize(Vimg ⊛ ctmr);  Then the inside test could be written as
177  so that V(x) = normalize((Vimg ⊛ ctmr)(x)).          pos ∈ dom(F)
178  Having this would simplify expression of standard LIC method, and  We could further extend this approach to allow geometric definitions of
179  would also help express other vector field expressions that arise  regions.  It might also be useful to do inside tests in world space,
180  in vector field feature exraction.  instead of image space.
181
182  Permit fields composition, especially for warping images by a  co- vs contra- index distinction
183  smooth field of deformation vectors
184    Permit field composition:
185    field#2(3)[3] warp = bspln3 ⊛ warpData;    field#2(3)[3] warp = bspln3 ⊛ warpData;
186    field#2(3)[] F = bspln3 ⊛ img;    field#2(3)[] F = bspln3 ⊛ img;
187    field#2(3)[] Fwarp = F ◦ warp;    field#2(3)[] Fwarp = F ◦ warp;
188  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.
189    This will be instrumental for expressing non-rigid registration
190    methods (but those will require co-vs-contra index distinction)
191
192  Allow the convolution to be specified either as a single 1D kernel  Allow the convolution to be specified either as a single 1D kernel
193  (as we have it now):  (as we have it now):
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.  What is very unclear is how, in such cases,  must be convolved with a different kernel during probing.
200  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
201  respect to some of the axes.  gradient, when we only want to differentiate with respect to some
202    subset of the axes.  One ambitious idea would be:
203  co- vs contra- index distinction    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
205      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  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
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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