Tagged Questions

The process of sorting or arranging entities into groups or categories; on a map, the process of representing members of a group by the same symbol, usually defined in a legend.

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3
votes
5answers
115 views

Which methods are most suited to classifying urban areas from Landsat imagery?

I am trying to use Landsat data to map urban extents over time. I need to perform a classification into built up / non built up areas. I am new to image classification. I have access to the following ...
0
votes
1answer
22 views

How do I classify or spot a pixel, based on a specific reflectance values of the six Landsat Bands using Erdas?

I have converted the DN values to the reflectance of a Landsat image to classify the rice field by its stages. To specify the reflectance values of each stages, I have sampled the reflectance values ...
5
votes
1answer
37 views

How to design class breaks for a time series of choropleth maps?

I'm working with a time series of choropleth maps showing the same indicator for the same administrative boundaries, but spanning period of nine years. What would be the most appropriate strategy of ...
0
votes
0answers
22 views

how separate Mixed classes

I am trying to deal with the aggregate data in Africover, I want to separate for example the mixed class – In North Kurdufan if I want the 6R from 2H/6R what is the a correct equation I have to write ...
2
votes
1answer
66 views

Image classification random forest [duplicate]

I am a newbie in R. I want to classify images using random forest in R. I am trying to learn the codes. But in the mean time, is there a push button (like a gui) in R that can be used for ...
0
votes
0answers
33 views

How to perform Neural Network Classification?

I'm using ENVI 4.8.There are some problems on parameters for Neural Network in Envi.(Envi-Classification-Supervised-Neural net) There are 5 bands and 12 classes that i have used for my study . The ...
2
votes
0answers
124 views

ISODATA unsupervised classification in ArcMap 10.1

I’m doing a project on landsat 5 images. I’ve composited the images into 1 raster, and I want to classify the raster with ISODATA Unsupervised Classification. How do I calculate the best number of ...
7
votes
2answers
90 views

How to classify agriculture employment data?

I have employment data which are huge - about 500 data for each category, like agriculture field, fishing field etc. Now I want to categorise this data in to 7 ranges. Suppose <50=1, >50-100=2, ...
6
votes
3answers
138 views

Classifying small structure in water using IR band

I was wondering how to identify small structures (eg. beacons) in a water body. I have worked with RGB images and its almost impossible to classify waterbodies in these images. How does IR band help ...
2
votes
2answers
197 views

Land use land cover change post- classification in ArcGIS for cross- tabulation

Please some one help me first I have finished the image classification process in another software package but many literary recommend Arc GIS package to process post-classification which means from ...
5
votes
3answers
156 views

Is it possible to automate the detection of clearcut areas in optical satellite imagery?

Given optical satellite or aerial imagery of a resolution similar to the image below, is it possible to accurately detect clearcut areas? Is their research or documentation that supports a specific ...
0
votes
2answers
52 views

Common class range for different attributes in a same polygon shapefile

I have a polygon shapefile which has population attributes pop90,pop91 and so on for 10 years. They have different minimum and maximum value for each of the years. Now I need to do classification for ...
6
votes
1answer
219 views

How to perform unsupervised classification of LANDSAT time series using Grass?

I'm using GRASS to perform an unsupervised classification on a time series of LANDSAT images (monthly temporal res, over 30 years), in order to compare land cover change in a particular area. I'm ...
1
vote
0answers
58 views

Segmentation Violation in ArcView 3.1 while performing UpdateLegend

I am loading a ".avl" legend file into ArcView 3.1 and I am plagued with a recurring Segmentation Violation Error when I execute the updatelegend command in the theme. It looks like the legend file ...
4
votes
1answer
352 views

How to train a signature file for supervised classification in ArcGIS 9.3

I wanna do supervised classification in ArcGIS 9.3. I have a 321RGB composite of a pretty good quality which I want to use for supervised classification. How can I create signature file which contains ...
3
votes
1answer
96 views

Convex Hull in SAGA Gis

How does one go about creating a convex hull from a set of points in SAGA GIS? I read that this is possible in QGIS, but I prefer SAGA and would like to see if it is possible. Furthermore, if it is ...
1
vote
1answer
130 views

How to merge different classes/clusters in one single raster in arcgis 9.3?

I've created a signature file with 8 clusters and performed an unsupervised classification. Later I have grouped values (spatial) classes together to form 4 classes I needed (in symbology) but that ...
2
votes
2answers
350 views

How to classify/style rasters correctly?

I am using a GeoTiff raster data and trying to classify it. I was wondering what are the techniques that I can use in QGIS to do this? The raster I have looks like but I tried the reclassify tool ...
3
votes
2answers
145 views

calculate coastline at risk

I have an idea of what I want to do but I don't know yet what tools will bring me there. I have administrative boundaries in one layer and coastline in another layer. The coastline is categorized in ...
1
vote
0answers
66 views

From classified image to topology in ArcInfo

I have some coastal 4 band imagery that I have classified to designate land, water, and undetermined. I want to convert this to polygons with topology, and significantly simplify the polygons. If I ...
1
vote
1answer
86 views

Symbology for specific values

I want to apply a symbology scheme for the final layer of my model. Rules are - All negative - Symbol A 0 - Symbol B All positive symbol C unknown - symbol D I am not sure how I can define these ...
6
votes
0answers
207 views

Land Classification with Spectral Python (SPy) [closed]

Does anyone have experience working with the Spectral Python module for land classification? The following k-means clustering example takes an iterative approach to classification through pixel ...
3
votes
1answer
153 views

Cloud and Snow Differentiation

I am doing unsupervised classification of a mountaneous terrain and I have used 500 classes to classify the land use. In my result, cloud and the snow are categorized in the same class. How do I ...
2
votes
2answers
641 views

How to vectorize a Raster-Classification? (qgis, grass)

I classified my raster-DHM into elevation levels using colormap. Its not a "real" classification, just a colormap. So I cant vectorize the classes to get polygones for every class. Whats the best ...
3
votes
3answers
314 views

Remote sensing: How to define landuse from remote sensing data?

I am trying to research ways into obtaining landuse data for a project which calculates the visual impacts of wind parks. I have a DEM and DOPs for a relatively large region (5000km²), but I have no ...
0
votes
1answer
641 views

How to automatically export multiple maps with quantile symbology?

I am a relatively new ArcGIS user and I have a question about automating a tedious join/symbology classification/export operation. I have a very simple shapefile to which I join a bunch of fields. I ...
5
votes
1answer
722 views

Open software tool or QGIS plug-in to make land cover classification

Is there any tool or plugin for QGIS/GRASS to make an automatic land cover classification from satellite imagery - based on CLC nomenclature for example? Of course, it will not be 100% sure but it ...
7
votes
1answer
816 views

Permanently Change ArcMap's “Maximum Sample Size” Setting?

I've lately been working on feature classes with a huge number of polygons (e.g. all of the Census blocks within the Chicago metro area). I've been needing to symbolize them by quantities a fair ...
2
votes
2answers
191 views

How to remove roads from dataset

I've got a shape file that I loaded into PostGIS that has both road and parcel multipolygons and I need to remove the roads. I tried loading the shp file in qgis and it loads them both as a single ...
0
votes
1answer
122 views

Problem running i.gensigset in Grass. Any ideas?

It just returns ERROR: Unable to create signature file. It doesn't say why... Anyone had this before and found a solution?

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