Hot answers tagged scale
12
In order to use scales on your map:
Set only the 'scales' option. Do not set maxResolution, minResolution, maxScale, minScale, numZoomLevels, or any other scale related property. Set it to an array of scale denominators (or scales).
Configure a unit: note that for meters, this should be 'm', for degrees, 'degrees', etc.
You can set a maxExtent. Do not set ...
12
This document presents an algorithm to do that:
Harrie, L., Sarjakoski, T., Lehto, L. A variable-scale map for small-display cartography. In: Joint International Symposium on GeoSpatial Theory, Processing and Applications (ISPRS/Commission IV, SDH2002). Ottawa, Canada, july 2002
An example:
EDIT:
This kind of representation is quite old. See the plan ...
10
Degrees of longitude get smaller as you move away from the equator, eventually going to 0 at the poles; degrees of latitude don't suffer the same fate (looking at the latitude and longitude lines on a globe will make this clearer).
Projecting your data to a coordinate system should solve the problem, because feet and meters don't change in size as you move ...
9
As the scale is a ratio, it doesn't have units itself. You can measure whatever you like on the map - one inch, one foot, one double-decker bus - and it will represent 6000 of the same unit in reality.
To give the scale in mixed units, you just have to know what 6000 inches are in feet - OnlineConversion tells me it's 500 feet - so you'd have 1 inch = 500 ...
7
How you'll go about solving this problem really depends on the case, and how important the actual topology is to you (versus just the visuals/rendering time). Since your final goal is to generalize coastlines, you may find some ideas on generalization useful.
One approach uses buffering, as seen here. I also had a similar problem a while ago and detailed my ...
7
If you don't have this capability built into your GIS, but you can perform some basic grid operations ("map algebra"), there is still a solution.
The calculation comes down to finding the slope of the route at every point. If you knew this exactly, with no discretization error, you would integrate the secant of the slope. On a grid, the integral is ...
7
SAGA GIS has a module for this: Interactive profile
http://www.saga-gis.org/saga_modules_doc/ta_profiles/index.html
The resulting points will contain the distance and the overland distance. If the DEM has a coarser resolution your overland distance will always be a bit lower (unless you have strange border conditions), but in reality this difference is ...
6
Your screen is probably running at 96 DPI, not 72.
Computing scale as a ratio of 1:n is a risky business at best with a web map. If your map is being displayed on an average monitor, you can assume 96DPI. But that will be wrong on (say) a mobile device, or a projector, or a 19" LCD running at 640x480 resolution, etc.
It is better to produce a scale bar ...
6
As @StephenLead said, ArcMap will Reproject your datasets on-the-fly. What is most critical is that each of your Datasets have the appropriate Coordinate System set beforehand. The other critical item is that you set the Coordinate System of your Data Frame. There are differing opinions as to what this should be set to, but a good rule is to set it to ...
6
You have to decide whether you want to enter coordinates in lat/lon, or from a background map with a projected CRS (e.g. in metres). For the first choice, you have to set the target CRS to WGS84 (EPSG:4326), and don't mix up lat and long values.
For the second choice, the target CRS must be set to the same CRS as the project CRS. This can be different from ...
5
Do you have your "backdrop (raster)"?
If yes, then there is two options:
it is georeferenced (in some non-earth coordinate system). Then everything is ok and you have just to use it with your vector data (if you have it already) or draw vector "polygons that will represent the rooms" using your raster as a background layer. In first case may be you will ...
5
Under the layer properties>labels tab you can setup multiple labeling classes (under the Method drop down) for your labeling scales. Labels can be rendered by query using the SQL Query button for each class. You can also use the Scale Range button to show or not show a certain class within certain scale ranges.
4
You could do it by defining your own projection;
Copy your current projection file
Open the copied file
Under Linear Unit select custom
Enter the number of metres per unit (eg, 10m for a pool)
Save this projection
Change the projection of your data frame to this new projection
Add your scale bar to the layout - it will have Unknown Units, but you should be ...
4
I am not clear what you mean by model-based-upscaling because, within your definition, moving-window approaches should be classed as model-based as they account for cells, their neighbours and some function of relationship or association (be it mean, max, min, std or whatever).
Essentially there are two ways to change the resolution of a raster:
...
4
This is a really interesting question, especially in the context of today where the quest is usually for more detail, higher resolution, etc. To directly answer your question, I think you are performing the exact correct operation.
As I see it, the reason for generalizing a layer is to reduce the size and complexity, for performance reasons. This might be ...
4
it is important to have all features within a map using the same GCS
and projection? Is this correct, or can I work across multiple GCS?
ArcMap will re-project your datasets on-the-fly if you have correctly set the coordinate systems beforehand. (There can be a performance hit from this, especially with rasters, but it will work.)
When I attempt ...
4
"google maps" has pre-defined scales with 20 pre-defined zoom Levels.
I am no expert, but maybe this is a hint:
20 : 1128.497220
19 : 2256.994440
18 : 4513.988880
17 : 9027.977761
16 : 18055.955520
15 : 36111.911040
14 : 72223.822090
13 : 144447.644200
12 : 288895.288400
11 : 577790.576700
10 : 1155581.153000
9 : 2311162.307000
8 : 4622324.614000
7 : ...
4
You must set the Project CRS to a projected CRS, for example the UTM zone for your part of the world. Thats different to the layers CRS, which might remain in degrees.
Measurement tool and scale bar look only at the project CRS, as long as on-the--fly-projection is enabled.
3
I found this formula on the ESRI Mapping Center Blog:
1/x = 1 / (pixel ground size [m/pixel] × pixel density [pixels/m]), so that 1 meter on the map represents x meters on the ground
Which, rearranged to solve for pixel density (resolution) is:
pixel density [pixels/m] = x / pixel ground size [m/pixel]
Plugging in my numbers/units this is:
...
3
I agree, the documentation is a bit limited when it comes to internationalization. For changing the text in controls, here's how it works (using German as an example language). First you need to import the language file into your html document:
<script src="<path to>/lib/OpenLayers/Lang/de.js" type="text/javascript"></script>
Then, set ...
3
Typically, a circle marker symbol is used to symbolize a point, not an area.
When working in a projected coordinated system that uses meters, you can use the following to get the width of a pixel in meters:
var pxWidth = map.extent.getWidth() / map.width;
While the geometry service provides a more robust implementation, you can also draw circles client ...
3
Just "my experience", but we tend to use Arial, bold at a 10 font size for the things we want to stand out on our maps (often with a 1.5 pt halo if we're using LIDAR or other sat imagery). This font stands out and is far easier to read than the fancier font choices. We usually make our maps for 11X17 sheet size, but not always (in reference to that choice ...
3
Web mercator and a specific set of scales have been adopted by all major mapping providers. Fo r more information on the choice behind using web mercator, see Why has Web Mercator (auxiliary sphere) become the web map standard?
The standard scales used by mapping providers are also well established. They are available several places online. I always ...
3
I think you are looking for Microsoft's Line Drive service http://msdn.microsoft.com/en-us/library/cc514631.aspx which produces maps like
You can read the original paper that it is based on at http://cs.ubc.ca/~tmm/courses/cpsc533c-03-spr/readings/rtmaps.pdf
3
I was happy to see @mwalker's answer but the comments that follow it indicate it did not end up addressing the OP's problem (as later modified). As it turns out in the updated version, we're actually talking about a much smaller discrepancy: the difference between 1:7489 and 1:7501 (0.16%). This amount is explainable by rounding to whole pixel coordinates ...
3
Have you checked each file to ensure that they have a defined coordinate system and have you established their datum? For example, you could have a mix of Geographic Coordinate system data (aka decimal degree) and projected data (eg. UTM etc etc) with their respective datums (eg WGS84, NAD83 etc etc). If some of your files don't have a defined coordinate ...
3
The scale bar can only be horizontal. However, you can rotate the rest of your layout 90° so the printed map looks like the scale bar is vertical. To simplify the process and save your neck from getting a crick in it, you can draft your layout in the orientation opposite of what you expect to finish on.
3
In the object properties (the scale bar) you must set two values, "segment size" and "map units per bar unit" (this second option is do for example a scale in KM rather then meters). In the next QGIS version there will be the option to force the scale be in meters or feet even when the project CRS is lat/lon.
3
You have tagged your question with OpenStreetMap, so I am assuming you are interested in the data in OSM's zoom levels.
Please have a look at: Zoom Levels
Usually you would not look at the whole world, at the same zoom level, as you would a small city. Your example is at zoom level 17, which has a scale of 1:4000.
You would look at the world either at ...
2
Use the MinimumResolution property on the Map control. This will allow you to zoom in to a smaller extent.
On a side note, it is recommended that you use the newer Web Mercator services rather than the old 4326 services. For imagery, the Web Mercator endpoint would be http://services.arcgisonline.com/ArcGIS/rest/services/World_Imagery/MapServer. See this ...
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