Better documentation for arcgisimage, basemap python -

i using arcgisimage api have map layers scatterplot.

however, documentation api, found here http://basemaptutorial.readthedocs.org/en/latest/backgrounds.html not good, concerning sizing of images:

xpixels sets zoom of image. bigger number ask bigger image, image have more detail. when zoom bigger, xsize must bigger maintain resolution

dpi image resolution @ output device. changing value change number of pixels, not zoom level

the xsize mentioned not defined anywhere, , doubling dpi between 300 , 600 doesn't affect size of image.

anyone have better documentation/tutorial?

i learning similar things...and new it. can offer simple ideas in mind. wish you.(although seems not so. ^_^ ) following code given example of tutorial adding adjustments. (la centered)

    mpl_toolkits.basemap import basemap     import matplotlib.pyplot plt      map = basemap(llcrnrlon=-118.5,llcrnrlat=33.15,urcrnrlon=-117.15,urcrnrlat=34.5, epsg=4269)     #http://server.arcgisonline.com/arcgis/rest/services     #epsg number of america 4269      map.arcgisimage(service='world_physical_map', xpixels = 1500, verbose= true)     plt.show() 

firstly, guess here "xsize" equals "xpixels", or should "size" (a misspelling? i'm not sure of that). told in tutorial, "xpixel" influence resolution of final figure , size of it.

when xpixels=150, you'll following picture (about 206kb): when xpixels=1500, you'll picture higher resolution (about 278kb). when zoom in figure out detail, picture clearer former one.

if want see picture bigger zoom, need set "xpixels" larger value keep clear.(that maintain resolution. guess gave out few simple explaination without many details.) , have no idea "dpi" used for...it first time cut cake 300 grids, second time cut 600 grids. figure won't clearer. , saying know neither become bigger graph.