IMAGE CLASSIFICATION

classic Classic list List threaded Threaded
5 messages Options
Reply | Threaded
Open this post in threaded view
|

IMAGE CLASSIFICATION

mavis chisha
Thank you very much for your reply.
 
However, i think the problem is on the import type.  I am importing the images using GEO TIFF but when it comes to creating a sample set,  it is not bringing the image domain for selection in order to create the classess.  When you comand the create button,  it tells you that "not a valid domain.  only image domain allowed".  Unfortunately even when selecting from the available domains,  the image domain is not appearing. 
 
I believe there could be another way of creating this image domain that the process will recognise.
 
I need help on this.
 
Kind regards
 
Mavis

_______________________________________________
Ilwis mailing list
[hidden email]
http://list.52north.org/mailman/listinfo/ilwis
http://ilwis.forum.52north.org
Reply | Threaded
Open this post in threaded view
|

Re: IMAGE CLASSIFICATION

Bas Retsios
Hello,

If you happen to have a "value" map and simply need to convert it to an "image" map, just to make one of the ILWIS applications happy, let ILWIS make a copy of the map with the correct domain.
Assumption: your map's filename is mymap.mpr, and its domain is "value" or similar (thus not "class" or "id" or "bool").
1. In the ILWIS command-line, type the formula output_map := mymap
2. The "Raster Map Definition" form will pop-up. In this form, focus on the Domain option. By default it is the same as the source-map. Change this to IMAGE. Note that the value-range and the precision changes.
3. Click OK. The map "output_map.mpr" now has the values of mymap.mpr, and Domain "image".
If you need some scaling/offsetting, e.g. to maximize the limited precision of the IMAGE domain, or to scale the map to match the value range of other maps, take care of that in the formula at (1).
E.g. if the values of mymap.mpr are between 0 and 1, and you would want to maximize the precision of domain IMAGE, multiply the map by 255:
output_map := 255 * mymap

Cheers,

Bas.


On 5/27/2013 13:10, mavis chisha wrote:
Thank you very much for your reply.
 
However, i think the problem is on the import type.  I am importing the images using GEO TIFF but when it comes to creating a sample set,  it is not bringing the image domain for selection in order to create the classess.  When you comand the create button,  it tells you that "not a valid domain.  only image domain allowed".  Unfortunately even when selecting from the available domains,  the image domain is not appearing. 
 
I believe there could be another way of creating this image domain that the process will recognise.
 
I need help on this.
 
Kind regards
 
Mavis


_______________________________________________
Ilwis mailing list
[hidden email]
http://list.52north.org/mailman/listinfo/ilwis
http://ilwis.forum.52north.org
Reply | Threaded
Open this post in threaded view
|

Re: IMAGE CLASSIFICATION

Bas Retsios
In reply to this post by mavis chisha
Hello,

Yes, the ILWIS command-line formula for generating new maps has two options:

1. a Definition symbol =
2. an Assignment symbol :=

From the ILWIS Help:

############################
By using the defintion symbol =, a dependent output map or a dependent output column will be created.

By using the assignment symbol :=, an editable map or column will be created. Dependency links are immediately broken after the output map or the output column has been calculated.

A dependent map or a dependent column has the following advantageous characteristics:
the formula/expression by which the map or column was created is stored (this is also called the definition of a map or column),
the formula/expression by which the output map or column was created can be changed/edited,
a series of dependent maps or columns can be recalculated/made up-to-date, when a single definition or a single input map or column has changed.
############################

In the example, I have used the assignment symbol := because then the result is "editable", thus you could e.g. change its georeference if needed .. also in many other cases the result it is simpler to use (e.g. copying it to another folder).

Cheers,

Bas.


On 5/27/2013 16:00, mavis chisha wrote:
Dear Bas Retsios,

Thank you very much for this valuable information. I will try it right away.

However,  i notice that you are adding full colons (:) when typing the command expressions.  Are they part of the expressions as well?

Kind regards,

Mavis

--- On Mon, 27/5/13, Bas Retsios [hidden email] wrote:

From: Bas Retsios [hidden email]
Subject: Re: [Ilwis] IMAGE CLASSIFICATION
To: "mavis chisha" [hidden email]
Cc: [hidden email]
Date: Monday, 27 May, 2013, 16:06

Hello,

If you happen to have a "value" map and simply need to convert it to an "image" map, just to make one of the ILWIS applications happy, let ILWIS make a copy of the map with the correct domain.
Assumption: your map's filename is mymap.mpr, and its domain is "value" or similar (thus not "class" or "id" or "bool").
1. In the ILWIS command-line, type the formula output_map := mymap
2. The "Raster Map Definition" form will pop-up. In this form, focus on the Domain option. By default it is the same as the source-map. Change this to IMAGE. Note that the value-range and the precision changes.
3. Click OK. The map "output_map.mpr" now has the values of mymap.mpr, and Domain "image".
If you need some scaling/offsetting, e.g. to maximize the limited precision of the IMAGE domain, or to scale the map to match the value range of other maps, take care of that in the formula at (1).
E.g. if the values of mymap.mpr are between 0 and 1, and you would want to maximize the precision of domain IMAGE, multiply the map by 255:
output_map := 255 * mymap

Cheers,

Bas.


On 5/27/2013 13:10, mavis chisha wrote:
Thank you very much for your reply.
 
However, i think the problem is on the import type.  I am importing the images using GEO TIFF but when it comes to creating a sample set,  it is not bringing the image domain for selection in order to create the classess.  When you comand the create button,  it tells you that "not a valid domain.  only image domain allowed".  Unfortunately even when selecting from the available domains,  the image domain is not appearing. 
 
I believe there could be another way of creating this image domain that the process will recognise.
 
I need help on this.
 
Kind regards
 
Mavis



_______________________________________________
Ilwis mailing list
[hidden email]
http://list.52north.org/mailman/listinfo/ilwis
http://ilwis.forum.52north.org
Reply | Threaded
Open this post in threaded view
|

Re: IMAGE CLASSIFICATION

Igor Savin
This post has NOT been accepted by the mailing list yet.
In reply to this post by mavis chisha
Dear Mavis,
The simplest way is to reinterpret range of the image values into diapazon from 0 to 255. After that you can change the domain value into image.
Of cource you will lost some information comparing with the initial image, but for many applications 0-255 is enough.
Try it.
with best regards,
Igor Savin
Reply | Threaded
Open this post in threaded view
|

Re: IMAGE CLASSIFICATION

deleoloruntoba
This post has NOT been accepted by the mailing list yet.
In reply to this post by mavis chisha
Hi all, please i seem to have an issue with using ILWIS 3.0 user guide with version 3.83. i want to carry out a multi spectral image classification. Following the user guide it says "The Sample Set editor will be started" after creating a sample set in the Create Sample Set dialog box. Please i do not mind if any one could assist me with what to do. Thanks.