How to clip map sheets to a Map Gird

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02-03-2017 11:17 AM
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New Contributor II

I have multiple geo referenced scanned maps from the 1950's, Like 60 of them.

I need to clip some white space off the edges so I can apply a fishnet.

So the main question is I have a 50k nts grid where the maps sit perfectly within each grid tile, When i try to clip the map to the grid it does nothing because it is reading the outside border of the nts grid. how would i get the clip to read each individual grid tile for a clip?

thanks

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MVP Honored Contributor

Have you tried select (the grid polygon), then clip?

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New Contributor II

I did selct a grid portion and created a layer form selcted data then proceeded to do the clip. 

Your way sounds easier.

Is there a way to script this for I have a lot of maps to do.

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MVP Honored Contributor

Yes, you could certainly do this with a Python script, looping through rasters, calculating raster centroid from extent, selecting the grid cell covering the centroid, doing the clip.

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New Contributor II

is there any good resources to script this

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MVP Honored Contributor

Start at the following link, get started on your script, and then post it back here when you need more help.

What is ArcPy?—ArcPy Get Started | ArcGIS Desktop 

Basically, figure out the geoprocessing tools you need, find and use the Python syntax on each tool's help page, and then put it in a for loop to repeat. But, first you need to figure out some Python.

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MVP Frequent Contributor

But if these are scanned map sheets, why not load them into a mosaic, then use the map polygon grid as the footprints.

This will auto magically leave behind all the stuff around the edge.

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New Contributor II

I like this idea!

So after i could split aprt the mosiac using split raster?

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Regular Contributor II

Prefect Answer,Neil Ayres Champion . It is it

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New Contributor II

so far i have this but no return on my clip

import arcpy

# Set the current workspace
arcpy.env.workspace = "Q:\\josephplessis\\GIS 307 Resource Managment\\Project\\Mapsheets\\soil"

#variables
R1 = "102I16"
R2 = "102I09"
R3 = "102I08"
R4 = "092L13"
R5 = "092L12"
R6 = "092L11"
R7 = "092L10"
R8 = "092L08"
R9 = "092L07"
R10 = "092L06"
R11 = "092L05"
R12 = "092L04"
R13 = "092L03"
R14 = "092L02"
R15 = "092L01"
R16 = "092E16"
R17 = "092E15"
R18 = "092E14"
R19 = "092E10"
R20 = "092E09"
R21 = "092E08"
R22 = "092E07"

# Local variables:
Output_Raster ="Q:\\josephplessis\\GIS 307 Resource Managment\\Project\\Geodatabases\\Grid_points.gdb\\gridlist.tif"

gridlist= R1,R2,R3,R4,R5,R6,R7,R8,R9,R10,R11,R12,R13,R14,R15,R16,R17,R18,R19,R20,R21,R22

grid="Q:\\josephplessis\\GIS 307 Resource Managment\\Project\\Geodatabases\\Grid_points.gdb\\GRID"

arcpy.MakeFeatureLayer_management(grid, "gridlyr")
arcpy.SelectLayerByAttribute_management("gridlyr", "NEW_SELECTION", " NTS_SNRC = 'gridlist' " )
print gridlist


# Get and print a list of TIFs from the workspace
rasters = arcpy.ListRasters("*", "TIF")
for raster in rasters:


print(raster)

while raster==gridlist:
arcpy.Clip_management("raster", Output_Raster, "gridlist", "", "", "NONE", "NO_MAINTAIN_EXTENT")

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