Annotation of /trunk/TODO

Parent Directory | Revision Log

---

Revision 1389 - (view) (download)

1 :	glk	1162	NOTE: GLK's approximate ranking of 8 most important tagged with
2 :	jhr	1115	[GLK:1], [GLK:2], ...
3 :
4 :	glk	1156	========================
5 :			SHORT TERM ============= (*needed* for streamlines & tractography)
6 :			========================
7 :	jhr	1115
8 :	glk	1338	[GLK:2] Add sequence types (needed for evals & evecs)
9 :	jhr	1115	syntax
10 :			types: ty '{' INT '}'
11 :			value construction: '{' e1 ',' … ',' en '}'
12 :			indexing: e '{' e '}'
13 :
14 :	glk	1338	[GLK:3] evals & evecs for symmetric tensor[2,2] and
15 :	glk	1162	tensor[3,3] (requires sequences)
16 :
17 :	glk	1156	ability to emit/track/record variables into dynamically re-sized
18 :	glk	1389	runtime output buffer
19 :	jhr	1115
20 :	jhr	1388	tensor fields: convolution on general tensor images (order > 1)
21 :	jhr	1115
22 :	glk	1156	========================
23 :	glk	1162	SHORT-ISH TERM ========= (to make using Diderot less annoying to
24 :			======================== program in, and slow to execute)
25 :	jhr	1115
26 :	glk	1167	Allow ".ddro" file extensions in addition to ".diderot"
27 :
28 :	glk	1204	Be able to output values of type tensor[2,2] and tensor[3,3];
29 :			(currently only scalars & vectors). Want to add some regression tests
30 :			based on this and currently can't
31 :	glk	1167
32 :	glk	1338	[GLK:1] Proper handling of stabilize method
33 :	jhr	1115
34 :	glk	1162	allow "*" to represent "modulate": per-component multiplication of
35 :			vectors, and vectors only (not tensors of order 2 or higher). Once
36 :			sequences are implemented this should be removed: the operation is not
37 :			invariant WRT basis so it is not a legit vector computation.
38 :
39 :			implicit type promotion of integers to reals where reals are
40 :			required (e.g. not exponentiation "^")
41 :
42 :	glk	1338	[GLK:4] Save Diderot output to nrrd, instead of "mip.txt"
43 :	jhr	1115	For grid of strands, save to similarly-shaped array
44 :			For list of strands, save to long 1-D (or 2-D for non-scalar output) list
45 :			For ragged things (like tractography output), will need to save both
46 :			complete list of values, as well as list of start indices and lengths
47 :			to index into complete list
48 :
49 :	glk	1389	[GLK:5] ability to declare a field so that probe positions are
50 :	glk	1120	*always* "inside"; with various ways of mapping the known image values
51 :			to non-existant index locations. One possible syntax emphasizes that
52 :			there is a index mapping function that logically precedes convolution:
53 :	glk	1162	F = bspln3 ⊛ (img ◦ clamp)
54 :	glk	1120	F = bspln3 ⊛ (img ◦ repeat)
55 :			F = bspln3 ⊛ (img ◦ mirror)
56 :			where "◦" or "∘" is used to indicate function composition
57 :	jhr	1115
58 :	glk	1162	Level of differentiability in field type should be statement about how
59 :			much differentiation the program *needs*, rather than what the kernel
60 :			*provides*. The needed differentiability can be less than or equal to
61 :			the provided differentiability.
62 :
63 :	glk	1156	Use ∇⊗ etc. syntax
64 :			syntax [DONE]
65 :			typechecking
66 :			IL and codegen
67 :	jhr	1115
68 :	glk	1156	Add type aliases for color types
69 :			rgb = real{3}
70 :			rgba = real{4}
71 :	jhr	1115
72 :	glk	1389	Revisit how images are created within the language.
73 :			The "load" operator should probably go away, and its strangs
74 :			that strings are there only as a way to refer to nrrd filenames
75 :
76 :	jhr	1115	==============================
77 :	glk	1156	MEDIUM TERM ================== (*needed* for particles)
78 :	jhr	1115	==============================
79 :
80 :			run-time birth of strands
81 :
82 :			"initially" supports lists
83 :
84 :	glk	1254	"initially" supports lists of positions output from different
85 :			initalization Diderot program (or output from the same program;
86 :			e.g. using output of iso2d.diderot for one isovalue to seed the input
87 :			to another invocation of the same program)
88 :	jhr	1115
89 :	glk	1156	Communication between strands: they have to be able to learn each
90 :			other's state (at the previous iteration). Early version of this can
91 :			have the network of neighbors be completely static (for running one
92 :			strand/pixel image computations). Later version with strands moving
93 :			through the domain will require some spatial data structure to
94 :			optimize discovery of neighbors.
95 :	jhr	1115
96 :	glk	1156	============================
97 :			MEDIUM-ISH TERM ============ (to make Diderot more useful/effective)
98 :			============================
99 :	jhr	1115
100 :	glk	1156	Python/ctypes interface to run-time
101 :	jhr	1115
102 :	glk	1156	support for Python interop and GUI
103 :	jhr	1115
104 :	glk	1162	Allow integer exponentiation ("^2") to apply to square matrices,
105 :			to represent repeated matrix multiplication
106 :
107 :	glk	1156	Put small 1-D and 2-D fields, when reconstructed specifically by tent
108 :			and when differentiation is not needed, into faster texture buffers.
109 :			test/illust-vr.diderot is good example of program that uses multiple
110 :			such 1-D fields basically as lookup-table-based function evaluation
111 :
112 :			extend norm (|exp|) to all tensor types [DONE for vectors and matrices]
113 :
114 :			determinant ("det") for tensor[3,3]
115 :
116 :	jhr	1115	add ":" for tensor dot product (contracts out two indices
117 :			instead of one like •), valid for all pairs of tensors with
118 :			at least two indices
119 :
120 :	glk	1156	test/uninit.diderot:
121 :			documents need for better compiler error messages when output variables
122 :			are not initialized; the current messages are very cryptic
123 :	jhr	1115
124 :			want: warnings when "D" (reserved for differentiation) is declared as
125 :			a variable name (get confusing error messages now)
126 :
127 :	glk	1156	==============================
128 :			LONG TERM ==================== (make Diderot more interesting/attractive from
129 :			============================== a research standpoint)
130 :	jhr	1115
131 :	glk	1389	[GLK:6] Want code-generation working for tensors of order three.
132 :			Order three matters for edge detection in scalar fields (to get
133 :			second derivatives of gradient magnitude), second derivatives
134 :			of vector fields (for some feature extraction), and first
135 :			derivatives of diffusion tensor fields.
136 :
137 :	glk	1156	IL support for higher-order tensor values (matrices, etc).
138 :			tensor construction [DONE]
139 :			tensor indexing [DONE]
140 :			tensor slicing
141 :	jhr	1115
142 :	glk	1156	Better handling of variables that determines the scope of a variable
143 :			based on its actual use, instead of where the user defined it. So,
144 :			for example, we should lift strand-invariant variables to global
145 :			scope. Also prune out useless variables, which should include field
146 :			variables after the translation to mid-il.
147 :
148 :			test/vr-kcomp2.diderot: Add support for code like
149 :			(F1 if x else F2)@pos
150 :			This will require duplication of the continuation of the conditional
151 :			(but we should only duplicate over the live-range of the result of the
152 :			conditional.
153 :
154 :	glk	1338	[GLK:7] Want: non-trivial field expressions & functions.
155 :	glk	1162	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 :	glk	1156	image(2)[2] Vimg = load(...);
160 :			field#0(2)[] Vlen = |Vimg ⊛ bspln3|;
161 :	glk	1162	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 :	glk	1156	field#2(2)[] F = Fimg ⊛ bspln3;
166 :			field#0(2)[] Gmag = |∇F|;
167 :	glk	1162	scalar field of squared gradient magnitude (simpler to differentiate):
168 :	glk	1156	field#2(2)[] F = Fimg ⊛ bspln3;
169 :			field#0(2)[] Gmsq = ∇F•∇F;
170 :	glk	1162	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)
172 :	glk	1156
173 :	jhr	1195	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 :	glk	1162	co- vs contra- index distinction
183 :	glk	1156
184 :	glk	1162	Permit field composition:
185 :	glk	1156	field#2(3)[3] warp = bspln3 ⊛ warpData;
186 :			field#2(3)[] F = bspln3 ⊛ img;
187 :			field#2(3)[] Fwarp = F ◦ warp;
188 :	glk	1162	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 :	glk	1156
192 :	glk	1155	Allow the convolution to be specified either as a single 1D kernel
193 :			(as we have it now):
194 :			field#2(3)[] F = bspln3 ⊛ img;
195 :			or, as a tensor product of kernels, one for each axis, e.g.
196 :			field#0(3)[] F = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img;
197 :	glk	1212	This is especially important for things like time-varying fields
198 :			and the use of scale-space in field visualization: one axis of the
199 :			must be convolved with a different kernel during probing.
200 :			What is very unclear is how, in such cases, we should notate the
201 :			gradient, when we only want to differentiate with respect to some
202 :			subset of the axes. One ambitious idea would be:
203 :	glk	1162	field#0(3)[] Ft = (bspln3 ⊗ bspln3 ⊗ tent) ⊛ img; // 2D time-varying field
204 :	glk	1204	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 :	glk	1155
207 :	glk	1204	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 :	glk	1162	representation of tensor symmetry
212 :	jhr	1115	(have to identify the group of index permutations that are symmetries)
213 :
214 :			dot works on all tensors
215 :
216 :			outer works on all tensors
217 :
218 :	glk	1204	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 :	jhr	1115	Einstein summation notation
235 :
236 :			"tensor comprehension" (like list comprehension)
237 :
238 :	glk	1204	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 :	jhr	1115	======================
248 :			BUGS =================
249 :			======================
250 :
251 :			test/zslice2.diderot:
252 :			// HEY (bug) bspln5 leads to problems ...
253 :			// uncaught exception Size [size]
254 :			// raised at c-target/c-target.sml:47.15-47.19
255 :			//field#4(3)[] F = img ⊛ bspln5;
256 :	glk	1336

---

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