ok, I will do. Thank you a lot for the suggestions. Stefano
> On Wed, May 14, 2014 at 03:23:35PM +0200, [email protected] wrote: >> I have 2.4 nm islands on a flat substrate. I would like to count them as >> precise as possible with Gwyddion. >> >> The procedure I'm following is to mark by threshold the islands and then >> in statistics check the number of grains. >> >> Unfortunately this number is not so precise, by hand i get 134 islands >> while with Gwyddion I get 294. The difference is too big. Moreover, if >> I >> change just a bit the threshold that number changes a lot. >> >> Instead, if I divide the projected area by pi times the square of the >> mean >> grain size (as if the grains were circles) I get a more reasonable >> number. >> >> Which method do you suggest? > > First, you can try other marking algorithms, such as Mark by Watershed > and Mark by Edge Detection. I'm also working on another method, but it > is not finished yet. > > I don't know if you get too many grains due to oversegmentation or > marking of areas that should not be marked as grains (e.g. small > few-pixel âgrainsâ caused by noise). But the currently available > methods are more prone to the latter. If this is the case, you can use > grain filtering to get rid of the extra grains. > > However, the area method may be still more robust. You can get good > threshold also from the height distribution or a Minkowski functional > and, if there is no serious under- or oversegmentation, divide the total > projected area by the median grain area. Median will likely to be > better than mean but you need to export the values for all grains using > Grains â Distribution, sort them and take the middle value. > > Regards, > > Yeti > > > ------------------------------------------------------------------------------ > "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE > Instantly run your Selenium tests across 300+ browser/OS combos. > Get unparalleled scalability from the best Selenium testing platform > available > Simple to use. Nothing to install. Get started now for free." > http://p.sf.net/sfu/SauceLabs > _______________________________________________ > Gwyddion-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/gwyddion-users > Stefano Chiodini, PhD Student Institute for Nanostructured Materials Studies (ISMN) National Research Council (CNR) Via Piero Gobetti 101 I-40129 Bologna I T A L Y Phone:++39-051-639-9188 Cell: ++39-3393142341 [email protected] www.bo.ismn.cnr.it ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Gwyddion-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/gwyddion-users
