'read_vel': reads one or two velocity fields and associated parameters from a file or a pair of files.
In the case of two velocity fields, the difference of the two fields (linearly interpolated to the positions of
the first field) is given as the default output. Any other operation on the two
fields can be introduced by an external function 'usrtransform'.
OBSOLETE: REPLACED BY read_ncfield
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[dt,time,pixcmx,pixcmy,vec_X,vec_Y,vec_Z,vec_U,vec_V,vec_W,vec_C,vec_F,fixflag,vel_type_out,error,nb_coord,nb_dim,Ima,CivStage]...
=read_vel(filename,vel_type,scal_type,vec_X_in,vec_Y_in,vec_Z_in);
OUTPUT:
dt:time interval of the image pair red from a single file, or vector with
two values for a pair of files
time: absolute time of the first file
pixcmx,pixcmy: scaling factors (from the first file)
vec_X,vec_Y,vec_Z: matlab vectors, representing the set of coordinates for
the velocity vectors, vec_Z=zeros(size(vec_X)) for a 2D planar field
vec_U,vec_V,vec_W: matlab vectors, representing the set of velocity components for
the velocity vectors, vec_W=zeros(size(vec_X)) for a 2 component field
vec_C: matlab vector, representing the set of image correlations, or any scalar set by the input 'scal_type'.
vec_F: matlab vector, representing the set of vector flags vec_F for quality warning.
fixflag: matlab vector, representing the set of vector flags for removal.
RMQ: when two fields are read, the flags and vec_C correspond
to the first field. By default vec_C=1,vec_F=1,fixflag=0 if
it is not defined. (faulse vectors of the second field are removed before interpolation)
vel_type_out: string representing the selected velocity type (civ1,civ2,filter1...)
error: error flag
error=0; OK
error=1; first field of file 1 not detected
error=2; second field of file 1 not detected
error=3; first field of file 2 not detected
error=4; second field of file 2 not detected
error=5; the scalar cannot be obtained
INPUT:
filename: cell of names (length 1 or 2) representing the file names.
vel_type: cell of imposed velocity types 'civ1','filter1'...if
vel_type={} or vel_type{1}=[], the best choice is made (first civ2, then civ1)
scal_type: string of a scalar name. If defined vec_C represents the value of this scalar
vec_X_in,vec_Y_in,vec_Z_in: optional imposed set of positions on which data are linearly interpolated (not yet implemented)
transform: transform.vel: name of an optional user defined function
[vec_U,vec_V,vec_W,vec_X,vec_Y,vec_Z]=usrtransform(vec_U,vec_V,vec_W,vec2_U,vec2_V,vec2_W,vec_X,vec_Y,vec_Z)
transform.scal: name of a transform function for a scalar (used if vec_C is a scalar)
FUNCTIONS called:
'varname_generator.m':, sets the names in the netcdf file from 'vel_type'
'read_netcdf.m': reads the netcdf file with a given set of variable names
'calc_scal.m': calculates the scalar (used for arrow colors)