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**1120**- (**download**) (**annotate**)*Thu May 5 08:18:26 2011 UTC*(9 years, 11 months ago) by*glk*File size: 6656 byte(s)

the road ahead

NOTE: GLK's approximate ranking of 5 most important tagged with [GLK:1], [GLK:2], ... ============================== other SHORT TERM ============= (including needed for LIC) ============================== 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). Level of differentiability in field type should be statement about how much differentiation the program *needs*, rather than what the kernel *provides*. The needed differentiability can be less than or equal to the provided differentiability. [GLK:1] Add sequence types (needed for evals & evecs) syntax types: ty '{' INT '}' value construction: '{' e1 ',' … ',' en '}' indexing: e '{' e '}' IL support for higher-order tensor values (matrices, etc). tensor construction [DONE] tensor indexing [DONE] tensor slicing verify that hessians work correctly [DONE] Use ∇⊗ etc. syntax syntax [DONE] typechecking IL and codegen test/uninit.diderot: documents need for better compiler error messages when output variables are not initialized; the current messages are very cryptic determinant ("det") for tensor[3,3] expand trace in mid to low translation value-numbering optimization Add type aliases for color types rgb = real{3} rgba = real{4} ============================== MEDIUM TERM ================== (including needed for streamlines & tractography) ============================== [GLK:1] evals & evecs for symmetric tensor[3,3] (requires sequences) [GLK:2] Save Diderot output to nrrd, instead of "mip.txt" For grid of strands, save to similarly-shaped array For list of strands, save to long 1-D (or 2-D for non-scalar output) list For ragged things (like tractography output), will need to save both complete list of values, as well as list of start indices and lengths to index into complete list [GLK:3] Use of Teem's "hest" command-line parser for getting any input variables that are not defined in the source file [GLK:4] ability to declare a field so that probe positions are *always* "inside"; with various ways of mapping the known image values to non-existant index locations. One possible syntax emphasizes that there is a index mapping function that logically precedes convolution: F = bspln3 ⊛ (img ◦ clamp) F = bspln3 ⊛ (img ◦ repeat) F = bspln3 ⊛ (img ◦ mirror) where "◦" or "∘" is used to indicate function composition extend norm (|exp|) to all tensor types [DONE for vectors and matrices] ability to emit/track/record variables into dynamically re-sized runtime buffer Want: allow 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. Want: non-trivial field expressions & functions: image(2)[2] Vimg = load(...); field#0(2)[] Vlen = |Vimg ⊛ bspln3|; to get a scalar field of vector length, or field#2(2)[] F = Fimg ⊛ bspln3; field#0(2)[] Gmag = |∇F|; to get a scalar field of gradient magnitude, or field#2(2)[] F = Fimg ⊛ bspln3; field#0(2)[] Gmsq = ∇F•∇F; to get a scalar field of squared gradient magnitude, which is simpler to differentiate. However, there is value in having these, even if 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. tensor fields: convolution on general tensor images ============================== other MEDIUM TERM ============ (needed for particles) ============================== [GLK:5] run-time death of strands; test/iso2d.diderot provides great initial test for "die" command. Put small 1-D and 2-D fields, reconstructed by tent, into faster texture buffers run-time birth of strands "initially" supports lists "initially" supports lists of positions output from different initalization Diderot program spatial data structure that permits strands' queries of neighbors proper handling of stabilize method test/vr-kcomp2.diderot: Add support for code like (F1 if x else F2)@pos This will require duplication of the continuation of the conditional (but we should only duplicate over the live-range of the result of the conditional. add ":" for tensor dot product (contracts out two indices instead of one like •), valid for all pairs of tensors with at least two indices ============================== other MEDIUM TERM ============ ============================== want: warnings when "D" (reserved for differentiation) is declared as a variable name (get confusing error messages now) support for Python interop and GUI Python/ctypes interface to run-time ============================== LONG TERM ==================== ============================== Better handling of variables that determines the scope of a variable based on its actual use, instead of where the user defined it. So, for example, we should lift strand-invariant variables to global scope. Also prune out useless variables, which should include field variables after the translation to mid-il. co- vs contra- index distinction some indication of tensor symmetry (have to identify the group of index permutations that are symmetries) dot works on all tensors outer works on all tensors Einstein summation notation "tensor comprehension" (like list comprehension) ====================== BUGS ================= ====================== test/read2vecs.diderot: // HEY (BUG?) shouldn't it be a type error to load this 2-D array of // 2-vectors into a 2-D *scalar* field? Instead, get: // uncaught exception Fail [Fail: Error in compiling lic.diderot] // raised at driver/main.sml:31.39-31.76 image(2)[] Vimg = load("../data/vorttest.nrrd"); test/zslice2.diderot: // HEY (bug) bspln5 leads to problems ... // uncaught exception Size [size] // raised at c-target/c-target.sml:47.15-47.19 //field#4(3)[] F = img ⊛ bspln5;

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