Exporting polygon features to individual image pngs

Question

I have a shapefile with a few thousand polygons, ArcGIS [9.3] (and even PostGIS). I would like to export each of those polygons into its own thumbnail image file without any real context. What is the best approach?

Answer 1

I know your question is tagged with ArcGIS but I thought it might be interesting to describe an approach that almost solves this problem using R (which is opensource and free). The idea is that you load in any shapefile, and then loop through the list of polygons printing each one out as a png. It is quite quick to produce each png ( a few seconds) - not sure how that compares to ArcGIS. The nice aspect about it is that the code is quite short.

library(maptools) # these are packages that you need to install
library(sp)

setwd("~/Dropbox/") # set working directory    
demo <- readShapePoly('pathtoShapefile/file.shp') # load data

# loop through all the polygons in the shapefile
for(i in 1:length(polygons(demo))) {     
    selected_polygon = demo[i,1]            
    thumbnail <- spplot(selected_polygon, scales=list(draw = F), colorkey=F) # remove scales and key/legend
    outFile = paste(i, '.png', sep='') # name the file using the loop counter
    png(outFile, height=200, width=200, units = 'px') # makes a png 200 x 200
    print(thumbnail); dev.off()
}

Here is an example of what is produced:

I'm not certain if it is possible to directly connect to PostGIS to read the data using the same approach.

Answer 2

A idea but without using ArcGIS, it might be possible to do it using GDAL and more specially gdal_rasterize: http://www.gdal.org/gdal_rasterize.html

I think that you would need be able to select each polygon using a "-where" statement, so feasibility might depend on your shapefile. You would also have to write some sort of script to avoid to avoid having to export each polygon manually.

Answer 3

You may also use ArcPy to zoom to each feature and export, see link below.

http://gis.utah.gov/code-python/python10-zoom-to-feature-export-layout

Answer 4

Data Driven Pages. use the shapefile for your index layer. Set up your layout so that you have no margins and it is the size of the PNG you want. To export, follow the instructions and the bottom of this page under "How to export Data Driven Pages to other formats using ArcMap": http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/Exporting_Data_Driven_Pages/00sm00000008000000/ Notice that you can modify the filename before exporting, so you can do a lot of custom combinations to get the PNG filename you want. (If you need help, post the attributes of an individual polygon and how you want the file name built.)