Diff of /branches/charisee/TODO

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	revision 1162, Mon May 9 18:56:15 2011 UTC	revision 1388, Fri Jun 24 14:45:33 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)	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
16	[GLK:4] evals & evecs for symmetric tensor[2,2] and	[GLK:3] evals & evecs for symmetric tensor[2,2] and
17	tensor[3,3] (requires sequences)	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 to	SHORT-ISH TERM ========= (to make using Diderot less annoying to
26	========================  program in, and slow to execute)	========================  program in, and slow to execute)
27
28	value-numbering optimization	value-numbering optimization [DONE]
29
30		Allow ".ddro" file extensions in addition to ".diderot"
31
32	[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];
33	three scalars:	(currently only scalars & vectors).  Want to add some regression tests
34	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
35
36	[GLK:2] Proper handling of stabilize method	[GLK:1] Proper handling of stabilize method
37
38	allow "*" to represent "modulate": per-component multiplication of	allow "*" to represent "modulate": per-component multiplication of
39	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 43
43	implicit type promotion of integers to reals where reals are	implicit type promotion of integers to reals where reals are
44	required (e.g. not exponentiation "^")	required (e.g. not exponentiation "^")
45
46	[GLK:5] 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:6] 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:7] 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:
#	Line 87	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 108	Line 107
107	Allow integer exponentiation ("^2") to apply to square matrices,	Allow integer exponentiation ("^2") to apply to square matrices,
108	to represent repeated matrix multiplication	to represent repeated matrix multiplication
109
	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.
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 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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