Timeline for A global, grid-like projection for creating heatmaps
Current License: CC BY-SA 3.0
22 events
| when toggle format | what | by | license | comment | |
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| Nov 30, 2014 at 23:28 | history | edited | PolyGeo♦ |
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| Sep 3, 2014 at 16:30 | answer | added | ragnvald | timeline score: 2 | |
| S Sep 3, 2014 at 13:04 | history | bounty ended | CommunityBot | ||
| S Sep 3, 2014 at 13:04 | history | notice removed | CommunityBot | ||
| Aug 29, 2014 at 7:33 | comment | added | GIS-Jonathan | @whuber - Thanks. I've updated the question with an edit and a screenshot to try and further clarify the use-case. | |
| Aug 29, 2014 at 7:32 | history | edited | GIS-Jonathan | CC BY-SA 3.0 |
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| Aug 28, 2014 at 11:52 | answer | added | radouxju | timeline score: 3 | |
| Aug 27, 2014 at 20:01 | comment | added | whuber | I'm pushing you a little bit because at bottom this really is a question about projections: grids--at least regular ones--can only exist within a projection onto a surface that is flat (or of negative curvature, but those aren't used in GIS!). Thus, any information you can supply about the intended use of your maps can inform the better answers and help you select among them. | |
| Aug 27, 2014 at 15:01 | comment | added | GIS-Jonathan | @whuber - You raise fair points but please trust that I'm aware of all that but believe it's generally irrelevant in this use-case, hence glossing over it. I'm showing a super-aggregated, very-high-level map that will indicate usage of a service. Source data ranges from ~30m resolution to 100km. I'm aggregating to grid cells of 1km upward. Unfortunately I don't know enough about projections to know about the advantages/disadvantages of each (and there are a lot), hence this question seeking based on what it'll be used for. | |
| Aug 27, 2014 at 14:50 | comment | added | whuber | I am sure you respect your users and would not want to present maps that could deceive them or otherwise be misread. When they look at your maps, they will be performing the analysis. What will they be concluding from what they see? If they will be reasoning about densities of variables, you owe it to them to use a projection that is approximately equal-area. If they will be using it to get compass bearings, you need a cylindrical projection; etc., etc. In any event, the MAUP will by highly relevant to anyone who wishes to rely on the data you present. | |
| Aug 27, 2014 at 14:48 | comment | added | GIS-Jonathan | @AnserGIS - The raw data is rectangular in nature, although some may be points to. I'm then counting how many of them are intersecting each of these grid-projection cells. See my other comment for why I'm not over-concerned about statistical accuracy. | |
| Aug 27, 2014 at 14:45 | comment | added | GIS-Jonathan | @whuber - The data will be used for general representation to lay-users, not any form of spatial analysis. Thus no particular preference relating to which geographical properties are kept/lost and MAUP is irrelevant as I'm seeking a gross generalisation of the data. I only need the grid-squares to neatly overlay something like OSM tiles. My desire for vector is because I'm storing it in a database and it's much easier to manipulate. | |
| Aug 27, 2014 at 13:50 | comment | added | AnserGIS | Could you clarify what the spatial dimensionality of the uderlying data is? i.e. is the data fundametally point and only aggregated to the cell, or is it actually areal? | |
| Aug 26, 2014 at 13:57 | history | tweeted | twitter.com/#!/StackGIS/status/504266405873983488 | ||
| Aug 26, 2014 at 13:39 | comment | added | whuber | Some information about the nature of the data and purpose of the heatmap will help focus the answers, which may (and ought to) vary according to what geographical properties you wish to preserve in the maps: orientation, bearing, area, shape, etc. Since reprojecting spatial data is relatively fast and easy, though, one might be led to discount these issues and focus instead on more fundamental ones of bias and accuracy: What do plan to do about the MAUP? Do you plan to draw any inferences from the data as binned into these grid cells? Why must it be a vector data structure? | |
| Aug 26, 2014 at 13:32 | answer | added | Russell at ISC | timeline score: 3 | |
| Aug 26, 2014 at 11:59 | history | edited | GIS-Jonathan | CC BY-SA 3.0 |
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| Aug 26, 2014 at 11:56 | comment | added | GIS-Jonathan | @John - Thanks; I came across the Military grid in my own searches, but it uses letters as well as numbers so I'm not sure it's suitable. The USNG stuff looks interesting but I'm not seeking to create my own. | |
| S Aug 26, 2014 at 11:54 | history | bounty started | GIS-Jonathan | ||
| S Aug 26, 2014 at 11:54 | history | notice added | GIS-Jonathan | Draw attention | |
| Aug 19, 2014 at 20:39 | comment | added | John | By no means necessarily a complete or perfect answer, but you may want to Google the Military Grid Reference System or at least the US National Grid fgdc.gov/usng for some ideas on how those organizations have handled at least similar challenges. Again, not necessarily perfect, but may be a good reference for your work. Hope it helps. | |
| Aug 19, 2014 at 20:32 | history | asked | GIS-Jonathan | CC BY-SA 3.0 |