ConvertToMD does not produces correct image any more

[Alex Buts]

If I produce MD image using the script below (the data for it are availible on the test server) and compare it with he image, produced by Horace, they look substantially different.

It was a time, where convert to MD was producing the images identical to Horace.

The workspaces contain identical number of events. Just appearance/arrangements are different.

P.S. Can not produce decent Mantid image as Sliceviewer SavePicture does not work any more. Ticket #8482 has been created to fix that.

# Sample script to build Mantid's combined MD workspace -- Horace sqw equivalent
config['defaultsave.directory']='/home/wkc26243/Fe400'
save_dir = config.getString('defaultsave.directory')
if len(save_dir) ==0 :
    config['defaultsave.directory']=os.getcwd()
    save_dir = config.getString('defaultsave.directory')
print "Data will be saved into: ",save_dir
config.appendDataSearchDir(save_dir)

print 'start\n'
cur_ws='wsn';
md_ws='mdws4D';
MDWSF='';


pars = dict();
pars['InputWorkspace']=''
pars['QDimensions']='Q3D'
pars['dEAnalysisMode']='Direct'
pars['Q3DFrames']='HKL'
pars['QConversionScales']='HKL'
pars['PreprocDetectorsWS']='preprDet'
pars['MinValues']='-7,-7,-7.,-72.0'
pars['MaxValues']='7.,7.,7.,382.0'
pars['SplitInto']=50
pars['MaxRecursionDepth']=1
pars['MinRecursionDepth']=1

for n in xrange(15052,15178+1):
	source = 'MAP'+str(n)+'.nxspe';
	target  = 'MDMAP'+str(n)+'.nxs';
	if not(os.path.exists(target )):
		print 'Converting ',source
		LoadNXSPE(Filename=source,OutputWorkspace=cur_ws)
		os.remove(source);
		SetUB(Workspace=cur_ws,a='2.87',b='2.87',c='2.87')
		# rotated by proper number of degrees around axis Y
		# AddSampleLog(Workspace=cur_ws,LogName='Psi',LogText=str(ic),LogType='Number Series')   -- sample log i shuld be already there 
		SetGoniometer(Workspace=cur_ws,Axis0='Psi,0,1,0,1')

		pars['InputWorkspace']=cur_ws;
		md_ws=ConvertToMD(**pars)

		SaveMD(md_ws,Filename=target  );
		DeleteWorkspace(md_ws);
		DeleteWorkspace(cur_ws);	
		
	if (len(MDWSF) == 0):
		MDWSF = target;
	else:
		MDWSF=MDWSF+','+target;


ws4D = MergeMDFiles(MDWSF,OutputFilename='fe400_8k.nxs',Parallel='0');
######################################################################

[Alex Buts]

Mantid image

[Alex Buts]

Horace Image

[Alex Buts]

refs #8488 This should fix it

Par file has the azimuthal angle sign convention opposite to the one, used by nxspe. To avoid any confusion, nxspe should always use one (right hand side) convention for azimuthal angle.

Changeset: b8de0f6f2eb0172cab55b79466963a5582edaaad

[Alex Buts]

Apparently, all differences were caused by different sign conventions between nxspe and par files.

to avoid any confusions, mantid will use its current convention event if par file is provided as data source.

the changes is trivial so testing easy to do through code review.

[Alex Buts]

refs #8488 should fix unit test

Changeset: c35bd1bc26603f9efd7eadb8c66ff281b467a3f1

[Alex Buts]

refs #8488 should fix it.

Changeset: de464df6fa75053df8af83fa0e960a44004326ef

[Alex Buts]

refs #8488 should fix unit test

but some thinking on what is actually happens in rings is needed

Changeset: f071fa104c9a76d5ae7882ea76229c8021d7b760

[Alex Buts]

refs #8488 final remarks

the minor one. Apparently all looks right.

Changeset: 16ab04d4adc204d623b7d176a960a2b9e3f4740c

[Alex Buts]

refs #8488 cpp check false positive suppressed

Changeset: 185eaef2666bd8e645a2cee8c32cc4823bad1976

[Alex Buts]

There were not one but two issues here.

One with the opposite sign of the azimuthal angle in external ascii par file wrt. the one used anywhere in mantid and another one -- invalid average detectors angular size for the situation when detector's angle range passes through -Pi to Pi (due to simple summation/average this would give 0 instead of +Pi or -Pi which it should be)

Easiest way to test this is to reduce and saveNXSPE for ISIS inelastic instruments (with 4 to 1 internal map) and check if Mslice image using detectors from nxspe is equivalent to the image obtained using phx file. (issue 2) and in horace, image produced without par file is equivalent to the image, produced with par file (possible only with latest horace). I did that and it works.

If tester is unfamiliar with the reduction and above mentioned programs, code review would allow to check if the changes address the issues mentioned above.

[Andrei Savici]

Merge remote-tracking branch 'origin/bugfix/8488_horace_ne_manitd'

Full changeset: ​35088428256a40b13969d6386135572341c6192e

[Andrei Savici]

Tested with some HYSPEC data. Everything seems fine

[Stuart Campbell]

This ticket has been transferred to github issue ​9332