06-20-2019 07:28 AM - last edited on 06-20-2019 08:09 AM by ian.anderson
hello , I am new to this website , so I am sorry if this is not where I am supposed to post my problem.
I am trying to apply an accuracy assesment for a classification image that i recoded to 4 classes using te recode tool in erdas imagine, I chose 1024 number of search count , 110 for the number of point and equalized random , then apply . I got the message saying this: 'reached the maximum number of search point 1024! so far collected 16 random coordinate. Would you like to continue with an other set of 1024 search points?'
then i press yes but this message keep comming up i, i press yes again but same thing happend again anad again, and the accuracy assesment doesn't finish .
Do you have any solution?
ps: I use Erdas imagine 2014
06-20-2019 08:12 AM
Sounds like the strategy you have chosen is not appropriate to the distribution of classes you have? Try a different strategy and/or increase the number of points to search (to give the algorithm a better chance of finding the number and distribution you have requested).
06-20-2019 08:54 AM - edited 06-20-2019 09:02 AM
What are the counts (histogram) for each class (including any background classes) in your image? If one (or more) of your classes has a small histogram count then it may be impossible (or very unlikely) to randomly include the required equalised number of pixels of that class and you will need to use one of the other strategies instead.
06-25-2019 01:08 AM
I have 11 class: from class1 to class10 and an unclassifes class,here are the histograms values for each class:
I recoded these classes using the recode tool to these new values:
After this, i applyed the accuracy assesment tool and then couldn't have the result because of the problem i mentionned in mu first message.
PS: I need only the classes recorded to: 1 , 2 and 3 . I didn't know how to delete the other class from the attribute table because the classification is a .img file .
06-25-2019 05:46 AM
The Unclassified class is huge compared to the others. Have you excluded it from the point creation process (by using the Select Classes button)? If not, the 1024 random points that get thrown down are almost always going to be in the Unclassified locations if you're using Equalized as the distribution strategy. Try excluding Unclassified, or try Stratified instead.
06-25-2019 05:56 AM
I selected only the classes that I want (using the Select Classes button as you mentionned), but still having that problem. Same thing even when I use the Stratified method.
06-25-2019 10:51 AM
That may be an issue with ERDAS IMAGINE 2014 then. You may wish to ocntact your local Support group for further assistance.