📤 Pull Request

Description

Now the program sfdiffsim receives velocity input as a command-line parameter. Because the program considers that all the received (t0,m0) pairs in the t0s and m0s files pertain to the same reflector in the stacked section. This is done in order to allow the program to run in a loop, it generates a set of diffraction hyperbolas for a given reflector in each iteration of the loop.

if(!sf_getfloat("v",&v)) sf_error("No v= hyperbolas velocity!");
	/* Hyperbolas velocity (Km/s)*/

Divide velocity by 2 because it uses the exploding reflector model to simulate diffractions in the stacked section.

	/* half medium velocity for diffraction */
	v=v/2;

Add an if condition to check if the calculated time sample is inside the section to avoid segmentation fault errors (it is the calculated time sample index, it can't be major than the number of the time samples in the section, nt0. i is the calculated CMP sample index, it can't be negative and major than the number of CMP samples in the section).

/* Jump to next iteration if its outside of the section */
			if(it >= nt0 || i >= nm0 || i < 0) continue;

Resolve #17

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Add images bellow and additional context if needed

Usage example of the new version of the program in a loop (use sfipick to do an iterative picking for each reflector and simulate diffractions hyperbolas in the stacked section with sfdiffsim).

# Loop over reflectors
numberOfReflectors = len(layers)
section = 'stackedSection'

for i in range(numberOfReflectors):

	reflectorPickedPoints = 'reflectorPickedPoints-%i.txt' % i
	t0sFile = 't0s-%i' % i
	t0sAscii = 't0s-%i.asc' %i
	m0sFile = 'm0s-%i' % i
	m0sAscii = 'm0s-%i.asc' % i
	returnedSection = 'returnedSection-%i' % i
	diffSection = 'diffSection-%i' % i

	# Reflector iterative Picking
	Flow(reflectorPickedPoints,section,
		'''
		ipick
		''')

	# Next step is done with 'ascFormat.sh' Shell Script
	# please check if the script have permissions to execute
	# Build t0 coordinates file (pass 1 to generate t0s file)
	Flow(t0sAscii,reflectorPickedPoints,
		'''
		./ascFormat.sh 1 %s
		''' % (t0sAscii))

	Flow(t0sFile,t0sAscii,'sfdd form=native')

	# Build m0 coordinates file (pass 2 to generate m0s file)
	Flow(m0sAscii,reflectorPickedPoints,
		'''
		./ascFormat.sh 2 %s
		''' % (m0sAscii))

	Flow(m0sFile,m0sAscii,'sfdd form=native')

	# Diffraction simulation in stacked section
	Flow([returnedSection,diffSection],[section,t0sFile,m0sFile],
		'''
		diffsim diff=${TARGETS[1]} aperture=1
		t0=${SOURCES[1]} m0=${SOURCES[2]} v=%g freq=10 verb=y
		''' % (velocities[i]))

	section = returnedSection

Image of the picking and diffraction simulation step (Available in creVelocityInversion package):