Viewing services

The content of the Topographical Sitemap is retrieved from different map databases, which means that differences can appear between different scales. For example, a municipal boundary can be shifted when zooming in the map image.

Some differences between scales will always be dependent on generalization to smaller scales.

Example of what a GetMap call might look like in a verification environment to display a map image from the Topographic Sitemap.The example shows which parameters from the technical description need to be used.

http://maps-ver.lantmateriet.se/topowebb/wms/v1?request=GetMap&version=1.1.1&layers=topowebbkartan&bbox=616576,6728032,617088,6728544&srs=epsg:3006&width=512&height=512&format=image/png

Due to a planned technical maintenance, the website has limited functionality during the current weekend.

For the call to work, it needs to sit together in a string.

There are no copyright parameters in the new spatial data services. All geographical information disseminated to the end customer must be marked on the client side.

In the Orthophoto Viewing service, there are WMS layers that show metadata with flight images and seam lines with aerial photo time.

In a GetMap call, the following parameters define the map image spread.

Calculation of a BBOX centered around a point is done as follows:

minE = centerE - pixel size * WIDTH / 2maxE = centerE + pixel size * WIDTH / 2minN = centerN - pixel size * HEIGHT / 2maxN = centerN + pixel size * HEIGHT / 2

"centerE", "centerN"Coordinates for the point around which the map image is to be centered, specified in e.g. SWEREF 99 TM

"pixel size (resolution)"Size of the map image's pixels on the ground, e.g. 5 m.

If you are interested in the map image being on a specific scale, you can"Pixel size" is calculated from the following formula:pixel size = scale factor * 0.0254 / 96,for a map image at a scale of 1:50 000, "scale factor = 50,000"

"WIDTH", "HEIGTH"Map image size in width resp. height specified in number of pixels, e.g. 500 px

The WMS standard is available in several versions. The ones being talked about are WMS 1.1.1 and WMS 1.3.0. The support for version 1.1.1 is greatest among both clients and WMS servers. Support for version 1.3.0 is starting to come in several clients and servers.

The biggest difference between the versions is the axis order when entering coordinates.WMS 1.1.1 is always Easting Norting, WMS 1.3.0 must follow the definition for the Reference / Coordinate system, which for Sweref99TM is Northing Easting.

This increases the complexity of implementing 1.3.0 on both the client and server side. There are also other differences that in some clients (for example some versions of ArcMap, AutoCad) do not seem to be implemented properly.

Place names are available in the own service OrtnamnDirekt and can be integrated with display service (s) in an application.

No, charts are not included in our databases.

In WMS, it is not possible to order a map image and enter a scale in the call. To define the map image, specify the geographical extent of the image, the boundary coordinates, and the width and height of the image in number of pixels.

The following formula is used to calculate the scale of a presented image.(The rendering services use 96 dpi image resolution to calculate scales.)

scale factor = pixel size * 96 / 0.0254 (pixel size is given in meters on the ground)Example:pixel size = 1 m / pxscale factor = 1 * 96 / 0.0254 = 3779scale 1: 3779

Conversely, image resolution can be calculated.pixel size = scale factor * 0.0254 / 96Example:scale 1: 3779pixel size = 3779 * 0.0254 / 96 m / p = 1 m / p

One last example where we want to order a map in scale 1: 5000.Prerequisites:* image width = 1000 pixels* image height (heigth) = 1000 pixels* minE = 670000* minN = 6500000* scale 1: 5000* image resolution 96 dpi

First, pixel size is calculated:pixel size = 5000 * 0.0254 / 96 m / p = 1,323 m / px

Then the geographical distribution of the image is calculated:maxE = 670000 + 1000 * 1.323 = 671323maxN = 6500000 + 1000 * 1.323 = 6501323

Thus, there are all the parameters for making a map order.

Is it because the services are set to "Geographic Coordinate System: GCS_WGS_1984" by default?

Yes, that's because WGS_1984 is the default. You have to make a setting in ArcMap yourself.

The image size is limited to 4096 x 4096 pixels.

The orthophotos shown are the most recent available for each area. This means that not all orthophotos shown are from the same year.

See overview with annual coverage of orthophotos from 2006 onwards (in Swedish, pdf, new window).

Many constituent subsets of the Topographic Web Map are updated at the following intervals:

• Topography 10, 1x/day.
• Topography 50.1 times/month.
• Topography 100, 1 time/month.
• Topography 250, 1 time/month.
• Topography 1M, 1 time/month.

MapServer.

No, that possibility is not currently offered.

Completely correct. Some of the services (eg Ortofoto Visning and Topographical Sitemap Visning, cache) are based on a pre-rendered tilepyramid in certain resolutions.

If the map is retrieved at the correct scale level, enlargement/reduction of the image is avoided and the best appearance/performance is achieved.

For detailed information, see the table that describes the fixed scale levels in the service, in the product description for e.g. Topographic Sitemap Display, cache.

The technical description for each service presents a complete list of which coordinate systems are supported.

Examples of reference systems:

PNG and JPEG. The GIF image format is no longer supported, it has been replaced by 8-bit png. The technical description of the services contains information on which formats are supported for each product.

WMS 1.1.1. and WMS 1.3.0.

If you as a user have connected correctly to the services and used the layer names and not the titles in your programming, no problems should arise.

No, at present, the services in ArcGIS Desktop and ArcGIS Online cannot be used.