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12

Most of the information can be found in Esri Help and some search, so I've just compiled some good reads. How coverages are stored? Since it is a proprietary format, you won't find any technical specifications on how the algorithms are implemented (unless @Vince will shed some light). Shapefiles came later on and were implemented as a standard which ...


9

The primary difference between these formats is the way that features relate to geometries. Back in the heyday of coverages, the coding language was FORTRAN, which meant fixed buffer sizes in COMMON blocks. The most restrictive of these was 500 vertices per line primitive ("arc"). This restriction introduced the concept of "pseudo-nodes" (places where ...


8

A "feature class" is an abstract name for source data for mapping. The origin of that data can be shapefile, file geodatabase, enterprise geodatabase, or any number of other sources (feature class factories). File and enterprise geodatabase sources are tables, with naming constraints that include: The initial character must be alphabetic The remaining ...


8

This is such a great question. Coverages, Shapefile and Geodatabases are fundamentally different geospatial data stores from an implementation standpoint as well as from a philosophical one. I'll try to summarize without going to deep into it. 1. Coverages: Coverages are interesting geospatial data structures. They concentrate on storing topology. So you ...


7

The location coordinates of your feature are stored in a geometry/shape field in the attribute table, not a text readable field you can adjust. You can store the coordinates as attributes, but they won't actually control where the point is. There are a few ways to address this: First, you could just make a table/spreadsheet/csv of your coordinate pairs. ...


6

There's some information on the OGC Call for Comments page on the new specification for coordinate reference system WKT standard. The original specification was written by Esri many moons ago for OGC based on the mid-1990s version of the EPSG Geodetic Parameter Dataset's schema. It was revised and extended by other OGC specifications. Because it was a very ...


5

Shp+shx is connected with dbf only by row number. If the order of features in shp remains the same you can just change dbf to a new version. But if shape number 1 gets written as the last feature in shp and #2 becomes #1 you will have all attributes wrong. Very dangerous. But perhaps, if the data provider writes an stable ID as an attribute in a trustworthy ...


5

Using Minimum Bounding Geometry with the "Convex Hull" option checked, should yield your results. EDIT While this answer it accepted and has 4 upvotes it is a wrong answer. The correct answer is to use "Concave Hull". See the details from the comments below.


5

From Census TIGER USA Shapefile


5

First... You can name a feature class whatever you like, as long as you dont use special characters. Almost, there is also a limitation on using a number as the first character. See this page. Can you have the feature class name be different than the shape file name? If I just rename the files have I renamed the feature classes? These are two ...


5

One more difference between the formats is that a geodatabase can model relationships between feature classes. As Ragi noted, Coverages work really well for edits that require awareness of topological relationships (imagine editing a parcel boundary). But this awareness exists only within a single coverage - if you want to model the relationships ...


5

This only a partial answer and lacks all python but too long to fit into a comment field. Your data is rather easy to convert into WKT: capture the coordinate part switch commas to spaces and spaces to commas close inside WKT polygon: POLYGON ((...)) POLYGON ((39.655756 -4.034769,39.655757 -4.034769,39.655758 -4.034769,39.655800 -4.034788,39.655885 ...


5

The coordinates in the attribute table are numeric values that are not linked with the geometry. If you want to create a large number of points with exact coordinates, I suggest that you create a table with those coordinates, then use create an XY table event that you can merge with your existing shapefile. If you need to move just a few points, then ...


4

What I'd probably do in ArcMap: Create a new feature class and start adding new features. As you place each point on the map, and note in your Excel file what the OBJECTID for the point is. Then, once you are done creating points, Join the Excel file to the feature class and the property owners can be copied over to the feature class. Another way in ArcMap: ...


4

As far as I know, it's still the case that you cannot use the M-part of geometries. I know that PostGIS supports M and it depends on your use case if that can be an alternative.


4

Try add Long, Lat columns after Name column in attribute table and calculate values via field calculator. When you save to CSV in save Options select GEOMETRY=Defaults (defoults this options set AS_XY) and you receive CSV file with only columns in attribute table of shapefile.


4

You can use ExecuteSQL on an OGR data source to return a new layer. E.g. from osgeo import ogr ogr_ds = ogr.Open('table.shp') sql = 'SELECT DISTINCT field FROM table' layer = ogr_ds.ExecuteSQL(sql) for i, feature in enumerate(layer): print('%d: %s' % (i, feature.GetField(0))) Note that there is no geometry in the layer, since it wasn't part of the SQL ...


4

To read your shapefile, i recommend you to use rgdal package and its readOGR function, or eventually use readShapeLines from maptools package. These packages rely on the sp package as concerning how the geospatial data is structured in R. You can do easily this to convert your shapefile into data.frame (ie extract the attributes of the shapefile) ...


3

There are three common methods to get shapefiles of your region of interest. Natural Earth. Select the areas of interest > export to new shapefile > dissolve Natural Earth Coastlines Global ADMN. Merge the countries of interest > Dissolve


3

It is the obscurity of Pseudo Mercator that leads to the offset. Both projections (3857 and 54004) share the same WKT definition, but it is treated differently. Google (Pseudo) Mercator takes lat/lon coordinates of the ellipsoid, and uses them as they were on a sphere. Hence the different definitions a=b= 6378137 in the proj string vs SPHEROID["WGS ...


3

Not sure whether it is what you are looking for (it depends on the action you want to perform). For example, let's use a shapefile of populated places. library(rgdal) shp <- "C:\path\to\shapefile" pts <- readOGR(shp,'ne_10m_populated_places_simple') OGR data source with driver: ESRI Shapefile Source: "C:\path\to\shapefile", layer: ...


3

I would use Python's itertools and a SearchCursor for a very efficient way to find the spatial relationships you are after. You can incorporate the geometry methods overlaps, contains, and equal to get at the geometry properties. Start off by creating a function to better organize the workflow and for repeatability def findOverlaps(x): Open a search ...


2

shp-to-osm.jar has a simple configuration file to translate shapefile attributes to SOM key-value pairs https://github.com/iandees/shp-to-osm http://wiki.openstreetmap.org/wiki/Shp-to-osm.jar


2

You can do it with JOSM + OpenData plugin. With this extension JOSM can open SHP (4326) than you can save it as OSM file


2

I'm not sure where you get the above-mentioned 'attribute' variable from, so I just assumed rownames(sp_df@data) (ranging from 0 to 193) as the desired output. Anyway, here is my approach that is probably not the fastest (or the most convenient in general), but it works. Basically, the script starts to loop through all the cells of the generated raster ...


2

So you need the area of all agriculture parcel for each dataset. There is a tool for this called "Saptial join". Use the JOIN_ONE_TO_ONE option, the sum field mapping rule and the "contain" relationship. No need to iterate. Note that you can use the spatial join of watersheds on the parcels in order to know the values from the corresponding watershed for ...


2

you could used shapely, here are some pieces of code that should help you build your script from shapely.geometry import Point, LineString for x in range(size): line = LineString([Point(leftX + x, 0), Point(leftX + x, 10000)]) clippedline = line.intersection(polygon)


2

Your workflow could be simplified if you connect the static geographical data with the changing database by a JOIN command. Details depends on the software you use. You need a unique field in both data to connect them.


2

That depends entirely upon how they prepare the SHP file. If sequence of records could change, then your hack won't work. If you are certain it is the same SHP+SHX file, then you can of course skip downloading it - that is no different from any other file that is the same as what you already have.


2

Just as Vince said...A simple tool built with model builder (using featureclass to featureclass or similar), then published to ArcGIS Server, would do the trick.



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