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13

I think the literal answer to your question is "not really" (aside from things like blue=water or blue/red=Dem/Rep). It depends on how/what other data is displayed on a map and the map's purpose whether, for example, county boundaries are a light color or dark color. There are plenty of places where color choice is discussed. Some examples of books (I'm ...


7

I don't have an answer for everything, but will give this a shot...I work for a utility setting up a GIS system for land acquisition, maintenance and engineering. We have a whole system of checks and balances where the behind-the-scenes IT server information is not something that I maintain, but can give you a glimpse of what we've seen with our production ...


7

Speaking purely from a data storage and analysis perspective, the geography type for PostGIS was designed with the antimeridian in mind (among several design goals). There are several functions specifically designed for the geography type. For instance, consider a LineString across Taveuni, Fiji (mapped with Great Circle Mapper), which straddles the ...


5

The thing about non-enterprise data storage is the users of this data frequently have changing/varying needs. In an enterprise setting it's not always most efficient to store data in central geodatabases, but it goes a long way in sticking people to standards, which can be taught and monitored. At the most basic level, a small company should house any "...


5

Used the Capacity Planning Tool to help compare one super heavy map service vs 4 lite map services, and the results indicate that the heavy map service is the way to go. This may not be the right answer, and the capacity planning tool does not take into account every factor (e.g. user workflows) - let me know via comments what you think. 1 super heavy ...


5

This is relative; best colours for associative data. I say this because, when I was doing geography in high school, it was quite the taboo to draw anything other than water on the map as blue. Often losing marks when we did, even getting close to purple was avoided. When I went to college, major highways were colored blue, in fact, a trademark blue; Nova ...


5

According to Corine Land Cover Legend, "industrial" is purple. This convention relies solely on solid colors, no hatchings or similar.


5

If your data is in a database then ideally you'd use a NULL value: a representation of "missing information and inapplicable information" However this could cause issues with client applications and code, and I don't believed NULL is supported in DBFs. What that value should be I guess is different for different organisational conventions. Whatever ...


5

I recently came across some of the work of Sidonie Christophe that has particular bearing to this subject. While in the particular paper I'm referencing (Christophe, 2011) she proposes a more general set of cartographic rules governing the choice of color for objects, the rules she proposes are so intuitive that I suspect they are in general implemented in ...


5

Current replies all give good advice. A general rule (from the scientific computing community) that works well in cases where you cannot store true nulls or NaNs is use the smallest (most negative) value the field will (validly) hold. Examples: A 7.2 decimal field can hold a value as small as -9999.99. An integer raster can hold numbers as small as -...


4

Most rasters I've come across use -9999.0 for floating point data as a convention, and GDAL will use -dbl_inf when you're writing code for an image that doesn't have a nodata/dummy value. 8-bit RGB will usually use 0 0 0 or 255 255 255, or have an alpha or mask channel. GML 3 coverages (for which there isn't a great deal of support at the moment, but that ...


4

I've stumbled over the following site http://www.planning.org/lbcs/standards/ (Land Based Classification Standards) Theres a PDF and a spreadsheet that define certain colours to certain types, But I agree with everyone here in saying it really depends on what your showing.


4

I like very much to talk about ArcObjects and that kind of discussion, but people may not find it suitable here. Well I always have a project for specific, ArcObjects code only. That means I can reuse these methods and classes anywhere else. (sounds like your Common). This is how I do it: Solution Business Project Models (this is how I name the ...


4

I would suggest to use multiple map services to take advantage between dynamic vs cached (tiled) services. For basemap data that does not change often you should use cached services (this will improve performance).


4

I would say that upside down text is definitely undesirable, particulary from the map user perspective. Its simply more natural to read from left to right even if the angle of the label is steep. (so my vote goes to the left picture ;) ) In this particular case however... since you have a long label... i would say, that its important to take into account ...


4

Borden Dent's excellent book Cartography: Thematic Map Design (I've got the 5th ed.) has a chapter on cartograms, in which he lists three potential problem areas with cartogram design: shape recognition (less of an issue with non-contiguous cartograms, since each unit is distinct) estimation of area magnitude (this is the problem you've identified: scaling ...


4

You cannot legally cache or store results from Google's Map API (with pretty narrow exceptions). From the Terms of Service (with emphasis added): 10.1.3 Restrictions against Data Export or Copying. ... (b) No Pre-Fetching, Caching, or Storage of Content. You must not pre-fetch, cache, or store any Content, except that you may store: (i) ...


4

If you need full database support with simultaneous user access handling, POSTGIS would be the best choice. As a first step on remote postgis access, see Connnect to PostGIS db using QGIS - when not on localhost See also: Best choice for building static maps: PostGIS, SpatiaLite or Shapefile?


3

There is no guaranteed correct because the symbolization and label placements depends on what is to be shown and to which audience (familiar patterns). So one needs to clarify the aims of the map before assessing the quality of its appearance. For automated labeling I would recommend to give a penalty for each violation of a desired rule and choose the ...


3

I agree that upside-down text is undesirable, and that the map's end user experience is paramount, but that doesn't necessarily mean that what feels most natural to read is always best. In your example, the lefthand image could actually be misleading. Reading 'Waverton' leads the viewer's eye towards the bottom of the page, and does not necessarily make the ...


3

Dave Bouwman wrote a helpful series 5 yrs ago about this. I would be very interested in hearing how his methodology has evolved since then. Geodatabase Kung-Fu: Geo-Business Objects Code Generation + Geodatabase = Goodness .NET Databinding the Geodatabase


3

I wont be able to give a great deal of information on this, but there are certain rules I think we need to follow for training sites: Training sites should be spread all over the image i.e. should be covering a large area and not just focussed in a region Just as Georeferencing, training sites should be identified at the corners and at points which give ...


3

I agree with Mapperz. Here are a few examples of the variety I found in a few seconds. (ok minutes;-) air traffic USGS DRG Cement Charts Bathymetry and many more


3

You can register a listener for the layer's tileerror event. Due to a documentation bug, this does not show up in the API docs. The tileerror listener receives an argument with a tile property, which is the OpenLayers.Tile.Image instance that failed to load.


2

I would use NaN because mathematical operations will produce other NaNs or throw exceptions. That way you can detectvearly that you are messing up because you are using a bogus value


2

The article below highlights some concepts regarding number of pixels per training site, and number of training sites per class for sampling (pg 2). Hawth's tools can be used to generate random stratified training points if you are using ArcGIS. Improving image classification accuracy: a method to incorporate uncertainty in the selection of training ...


2

Though I am not too experienced with spatial data management, I found the following Software-Carpentry.org video tutorial (discussing general data management practices, widely applicable to various scenarios) pretty helpful: Data Management


2

PostGIS can do what you're talking about. I have it set up on a laptop for personal use, but if I wanted to expand it out simply dumping the data and loading it onto a more traditional server would be sufficient. You can use Postgres's roles to define admin and read only accounts. To back up the data you can set up a cron job that runs pg_dump and ...


2

When viewing anything in a geographic coordinate system in GIS software, it is not unprojected. It still has to be displayed on your 2-dimensional computer screen. Usually this uses a latitude/longitude grid in a type of equirectangular projection known as plate carrée. This would produce a very strange result in your georeferencing, since your source map is ...



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