Spherical Harmonics Decomposition of a surface's coordinates or data
Model:
Given a data vector 'd' defined over the domain of N nodes of surface 'S'
The weighted spherical harmonics representation of d (termed Sd) is given by:
L l -l(l+1)s
Sd = SUM SUM e B Y
l=0 m=-l l,m l,m
where
L: Largest degree of spherical harmonics
Y : Spherical harmonic of degree l and order m
l,m
Y is an (L+1 by N) complex matrix.
B : Coefficient associated with harmonic Y
l,m l,m
s: Smoothing parameter ranging between 0 for no smoothing
and 0.1 for the extreme smoothing. The larger s, the higher
the attenuation of higher degree harmonics.
Small values of s (0.005) can be used to reduce Gibbs ringing artifacts.
Usage:
SpharmDeco <-i_TYPE S> -unit_sph UNIT_SPH_LABEL> <-l L>
[<-i_TYPE SD> ... | <-data D>]
[-bases_prefix BASES]
[<-prefix PREFIX>] [<-o_TYPE SDR> ...]
[-debug DBG] [-sigma s]
Input:
-i_TYPE S: Unit sphere, isotopic to the surface domain over which the
data to be decomposed is defined.
This surface is used to calculate the basis functions
up to order L.
These basis functions are saved under
the prefix BASES_PREFIX.
Note that this surface does not need to be of
radius 1.
-unit_sph UNIT_SPH_LABEL: Provide the label of the unit sphere.
If you do not do that, the program won't know
which of the two -i_TYPE options specifies the
unit sphere.
-l L: Decomposition order
One of:
-i_TYPE SD: A surface that is isotopic to S and whose node coordinates
provide three data vectors (X, Y, Z) to be decomposed
See help section on surface input to understand the
syntax of -i_TYPE
You can specify multiple surfaces to be processed by
using repeated instances of -i_TYPE SD option. This is more
computationally efficient than doing each surface separately. or
-data D: A dataset whose K columns are to be individually decomposed.
-bases_prefix BASES_PREFIX: If -unit_sph is used, this option save the
bases functions under the prefix BASES_PREFIX
Otherwise, if BASES_PREFIX exists on disk, the
program will reload them. This is intended to
speed up the program, however, in practice,
this may not be the case.
Note that the bases are not reusable with a
different unit sphere.
-debug DBG: Debug levels (1-3)
-sigma s: Smoothing parameter (0 .. 0.001) which weighs down the
contribution of higher order harmonics.
-prefix PREFIX: Write out the reconstructed data into dataset PREFIX
and write the beta coefficients for each processed
data column. Note that when you are using node
coordinates form J surfaces, the output will be for
3*J columns with the 1st triplet of columns for the first
surface's X Y Z coordinates and the 2nd triplet for the
second surface's coordinates, etc.
-o_TYPE SDR: Write out a new surface with reconstructed coordinates.
This option is only valid if -i_TYPE SD is used.
See help section on surface output to understand the
syntax of -o_TYPE.
If you specify multiple (M) SD surfaces, you will get M
reconstructed surfaces out. They can be named in one of
two ways depending on how many -o_TYPE options you use.
If only one -o_TYPE is used, then M names are automatically
generated by appending .sXX to SDR. Alternately, you can
name all the output surfaces by using M -o_TYPE options.
Output files:
Harmonics of each order l are stored in a separate
file with the order l in its name. For example for l = 3, the harmonics
are stored in a file called BASES_PREFIX.sph03.1D.
In the simplest form, this file is in .1D format and contains an
(l+1 x N) complex matrix. The real part constitutes the negative degree
harmonics and the positive part contains the positive degree ones.
(Internally, the complex matrix is turned into a real matrix of size
2l+1 x N )
Beta coefficients are stored in one for each of the input K data columns.
For example the beta coefficients for the data column 2 is called:
PREFIX.beta.col002.1D.dset.
The (l+1 x 2l+1) matrix in each file in real valued with each row
containing coefficients that for order l.
Surface or data reconstruction files are named based on PREFIX.
This program is based on Moo Chung's matlab implementation of spherical
harmonics decomposition which is presented in:
Chung, M.K., Dalton, K.M., Shen, L., L., Evans, A.C., Davidson, R.J. 2006.
Unified cortical surface morphometry and its application to quantifying
amount of gray matter.
Technical Report 1122.
Department of Statistics, University of Wisconsin-Madison.
http://www.stat.wisc.edu/~mchung/papers/TR1122.2006.pdf
-------------------------------------------
For examples, see script @Spharm.examples
-------------------------------------------
Specifying input surfaces using -i or -i_TYPE options:
-i_TYPE inSurf specifies the input surface,
TYPE is one of the following:
fs: FreeSurfer surface.
If surface name has .asc it is assumed to be
in ASCII format. Otherwise it is assumed to be
in BINARY_BE (Big Endian) format.
Patches in Binary format cannot be read at the moment.
sf: SureFit surface.
You must specify the .coord followed by the .topo file.
vec (or 1D): Simple ascii matrix format.
You must specify the coord (NodeList) file followed by
the topo (FaceSetList) file.
coord contains 3 floats per line, representing
X Y Z vertex coordinates.
topo contains 3 ints per line, representing
v1 v2 v3 triangle vertices.
ply: PLY format, ascii or binary.
Only vertex and triangulation info is preserved.
stl: STL format, ascii or binary.
This format of no use for much of the surface-based
analyses. Objects are defined as a soup of triangles
with no information about which edges they share. STL is only
useful for taking surface models to some 3D printing
software.
mni: MNI .obj format, ascii only.
Only vertex, triangulation, and node normals info is preserved.
byu: BYU format, ascii.
Polygons with more than 3 edges are turned into
triangles.
bv: BrainVoyager format.
Only vertex and triangulation info is preserved.
dx: OpenDX ascii mesh format.
Only vertex and triangulation info is preserved.
Requires presence of 3 objects, the one of class
'field' should contain 2 components 'positions'
and 'connections' that point to the two objects
containing node coordinates and topology, respectively.
gii: GIFTI XML surface format.
obj: OBJ file format for triangular meshes only. The following
primitives are preserved: v (vertices), f (faces, triangles
only), and p (points)
Note that if the surface filename has the proper extension,
it is enough to use the -i option and let the programs guess
the type from the extension.
You can also specify multiple surfaces after -i option. This makes
it possible to use wildcards on the command line for reading in a bunch
of surfaces at once.
-onestate: Make all -i_* surfaces have the same state, i.e.
they all appear at the same time in the viewer.
By default, each -i_* surface has its own state.
For -onestate to take effect, it must precede all -i
options with on the command line.
-anatomical: Label all -i surfaces as anatomically correct.
Again, this option should precede the -i_* options.
More variants for option -i:
-----------------------------
You can also load standard-mesh spheres that are formed in memory
with the following notation
-i ldNUM: Where NUM is the parameter controlling
the mesh density exactly as the parameter -ld linDepth
does in CreateIcosahedron. For example:
suma -i ld60
create on the fly a surface that is identical to the
one produced by: CreateIcosahedron -ld 60 -tosphere
-i rdNUM: Same as -i ldNUM but with NUM specifying the equivalent
of parameter -rd recDepth in CreateIcosahedron.
To keep the option confusing enough, you can also use -i to load
template surfaces. For example:
suma -i lh:MNI_N27:ld60:smoothwm
will load the left hemisphere smoothwm surface for template MNI_N27
at standard mesh density ld60.
The string following -i is formatted thusly:
HEMI:TEMPLATE:DENSITY:SURF where:
HEMI specifies a hemisphere. Choose from 'l', 'r', 'lh' or 'rh'.
You must specify a hemisphere with option -i because it is
supposed to load one surface at a time.
You can load multiple surfaces with -spec which also supports
these features.
TEMPLATE: Specify the template name. For now, choose from MNI_N27 if
you want to use the FreeSurfer reconstructed surfaces from
the MNI_N27 volume, or TT_N27
Those templates must be installed under this directory:
/home/afniHQ/.afni/data/
If you have no surface templates there, download
https://afni.nimh.nih.gov/pub/dist/tgz/suma_MNI_N27.tgz
and/or
https://afni.nimh.nih.gov/pub/dist/tgz/suma_TT_N27.tgz
and/or
https://afni.nimh.nih.gov/pub/dist/tgz/suma_MNI152_2009.tgz
and untar them under directory /home/afniHQ/.afni/data/
DENSITY: Use if you want to load standard-mesh versions of the template
surfaces. Note that only ld20, ld60, ld120, and ld141 are in
the current distributed templates. You can create other
densities if you wish with MapIcosahedron, but follow the
same naming convention to enable SUMA to find them.
SURF: Which surface do you want. The string matching is partial, as long
as the match is unique.
So for example something like: suma -i l:MNI_N27:ld60:smooth
is more than enough to get you the ld60 MNI_N27 left hemisphere
smoothwm surface.
The order in which you specify HEMI, TEMPLATE, DENSITY, and SURF, does
not matter.
For template surfaces, the -sv option is provided automatically, so you
can have SUMA talking to AFNI with something like:
suma -i l:MNI_N27:ld60:smooth &
afni -niml /home/afniHQ/.afni/data/suma_MNI_N27
Specifying a surface specification (spec) file:
-spec SPEC: specify the name of the SPEC file.
As with option -i, you can load template
spec files with symbolic notation trickery as in:
suma -spec MNI_N27
which will load the all the surfaces from template MNI_N27
at the original FreeSurfer mesh density.
The string following -spec is formatted in the following manner:
HEMI:TEMPLATE:DENSITY where:
HEMI specifies a hemisphere. Choose from 'l', 'r', 'lh', 'rh', 'lr', or
'both' which is the default if you do not specify a hemisphere.
TEMPLATE: Specify the template name. For now, choose from MNI_N27 if
you want surfaces from the MNI_N27 volume, or TT_N27
for the Talairach version.
Those templates must be installed under this directory:
/home/afniHQ/.afni/data/
If you have no surface templates there, download one of:
https://afni.nimh.nih.gov/pub/dist/tgz/suma_MNI_N27.tgz
https://afni.nimh.nih.gov/pub/dist/tgz/suma_TT_N27.tgz
https://afni.nimh.nih.gov/pub/dist/tgz/suma_MNI152_2009.tgz
and untar them under directory /home/afniHQ/.afni/data/
DENSITY: Use if you want to load standard-mesh versions of the template
surfaces. Note that only ld20, ld60, ld120, and ld141 are in
the current distributed templates. You can create other
densities if you wish with MapIcosahedron, but follow the
same naming convention to enable SUMA to find them.
This parameter is optional.
The order in which you specify HEMI, TEMPLATE, and DENSITY, does
not matter.
For template surfaces, the -sv option is provided automatically, so you
can have SUMA talking to AFNI with something like:
suma -spec MNI_N27:ld60 &
afni -niml /home/afniHQ/.afni/data/suma_MNI_N27
Specifying output surfaces using -o or -o_TYPE options:
-o_TYPE outSurf specifies the output surface,
TYPE is one of the following:
fs: FreeSurfer ascii surface.
fsp: FeeSurfer ascii patch surface.
In addition to outSurf, you need to specify
the name of the parent surface for the patch.
using the -ipar_TYPE option.
This option is only for ConvertSurface
sf: SureFit surface.
For most programs, you are expected to specify prefix:
i.e. -o_sf brain. In some programs, you are allowed to
specify both .coord and .topo file names:
i.e. -o_sf XYZ.coord TRI.topo
The program will determine your choice by examining
the first character of the second parameter following
-o_sf. If that character is a '-' then you have supplied
a prefix and the program will generate the coord and topo names.
vec (or 1D): Simple ascii matrix format.
For most programs, you are expected to specify prefix:
i.e. -o_1D brain. In some programs, you are allowed to
specify both coord and topo file names:
i.e. -o_1D brain.1D.coord brain.1D.topo
coord contains 3 floats per line, representing
X Y Z vertex coordinates.
topo contains 3 ints per line, representing
v1 v2 v3 triangle vertices.
ply: PLY format, ascii or binary.
stl: STL format, ascii or binary (see also STL under option -i_TYPE).
byu: BYU format, ascii or binary.
mni: MNI obj format, ascii only.
gii: GIFTI format, ascii.
You can also enforce the encoding of data arrays
by using gii_asc, gii_b64, or gii_b64gz for
ASCII, Base64, or Base64 Gzipped.
If AFNI_NIML_TEXT_DATA environment variable is set to YES, the
the default encoding is ASCII, otherwise it is Base64.
obj: No support for writing OBJ format exists yet.
Note that if the surface filename has the proper extension,
it is enough to use the -o option and let the programs guess
the type from the extension.
SUMA communication options:
-talk_suma: Send progress with each iteration to SUMA.
-refresh_rate rps: Maximum number of updates to SUMA per second.
The default is the maximum speed.
-send_kth kth: Send the kth element to SUMA (default is 1).
This allows you to cut down on the number of elements
being sent to SUMA.
-sh <SumaHost>: Name (or IP address) of the computer running SUMA.
This parameter is optional, the default is 127.0.0.1
-ni_text: Use NI_TEXT_MODE for data transmission.
-ni_binary: Use NI_BINARY_MODE for data transmission.
(default is ni_binary).
-feed_afni: Send updates to AFNI via SUMA's talk.
-np PORT_OFFSET: Provide a port offset to allow multiple instances of
AFNI <--> SUMA, AFNI <--> 3dGroupIncorr, or any other
programs that communicate together to operate on the same
machine.
All ports are assigned numbers relative to PORT_OFFSET.
The same PORT_OFFSET value must be used on all programs
that are to talk together. PORT_OFFSET is an integer in
the inclusive range [1025 to 65500].
When you want to use multiple instances of communicating programs,
be sure the PORT_OFFSETS you use differ by about 50 or you may
still have port conflicts. A BETTER approach is to use -npb below.
-npq PORT_OFFSET: Like -np, but more quiet in the face of adversity.
-npb PORT_OFFSET_BLOC: Similar to -np, except it is easier to use.
PORT_OFFSET_BLOC is an integer between 0 and
MAX_BLOC. MAX_BLOC is around 4000 for now, but
it might decrease as we use up more ports in AFNI.
You should be safe for the next 10 years if you
stay under 2000.
Using this function reduces your chances of causing
port conflicts.
See also afni and suma options: -list_ports and -port_number for
information about port number assignments.
You can also provide a port offset with the environment variable
AFNI_PORT_OFFSET. Using -np overrides AFNI_PORT_OFFSET.
-max_port_bloc: Print the current value of MAX_BLOC and exit.
Remember this value can get smaller with future releases.
Stay under 2000.
-max_port_bloc_quiet: Spit MAX_BLOC value only and exit.
-num_assigned_ports: Print the number of assigned ports used by AFNI
then quit.
-num_assigned_ports_quiet: Do it quietly.
Port Handling Examples:
-----------------------
Say you want to run three instances of AFNI <--> SUMA.
For the first you just do:
suma -niml -spec ... -sv ... &
afni -niml &
Then for the second instance pick an offset bloc, say 1 and run
suma -niml -npb 1 -spec ... -sv ... &
afni -niml -npb 1 &
And for yet another instance:
suma -niml -npb 2 -spec ... -sv ... &
afni -niml -npb 2 &
etc.
Since you can launch many instances of communicating programs now,
you need to know wich SUMA window, say, is talking to which AFNI.
To sort this out, the titlebars now show the number of the bloc
of ports they are using. When the bloc is set either via
environment variables AFNI_PORT_OFFSET or AFNI_PORT_BLOC, or
with one of the -np* options, window title bars change from
[A] to [A#] with # being the resultant bloc number.
In the examples above, both AFNI and SUMA windows will show [A2]
when -npb is 2.
[-novolreg]: Ignore any Rotate, Volreg, Tagalign,
or WarpDrive transformations present in
the Surface Volume.
[-noxform]: Same as -novolreg
[-setenv "'ENVname=ENVvalue'"]: Set environment variable ENVname
to be ENVvalue. Quotes are necessary.
Example: suma -setenv "'SUMA_BackgroundColor = 1 0 1'"
See also options -update_env, -environment, etc
in the output of 'suma -help'
Common Debugging Options:
[-trace]: Turns on In/Out debug and Memory tracing.
For speeding up the tracing log, I recommend
you redirect stdout to a file when using this option.
For example, if you were running suma you would use:
suma -spec lh.spec -sv ... > TraceFile
This option replaces the old -iodbg and -memdbg.
[-TRACE]: Turns on extreme tracing.
[-nomall]: Turn off memory tracing.
[-yesmall]: Turn on memory tracing (default).
NOTE: For programs that output results to stdout
(that is to your shell/screen), the debugging info
might get mixed up with your results.
Global Options (available to all AFNI/SUMA programs)
-h: Mini help, at time, same as -help in many cases.
-help: The entire help output
-HELP: Extreme help, same as -help in majority of cases.
-h_view: Open help in text editor. AFNI will try to find a GUI editor
-hview : on your machine. You can control which it should use by
setting environment variable AFNI_GUI_EDITOR.
-h_web: Open help in web browser. AFNI will try to find a browser.
-hweb : on your machine. You can control which it should use by
setting environment variable AFNI_GUI_EDITOR.
-h_find WORD: Look for lines in this programs's -help output that match
(approximately) WORD.
-h_raw: Help string unedited
-h_spx: Help string in sphinx loveliness, but do not try to autoformat
-h_aspx: Help string in sphinx with autoformatting of options, etc.
-all_opts: Try to identify all options for the program from the
output of its -help option. Some options might be missed
and others misidentified. Use this output for hints only.
Compile Date:
Oct 17 2024
