Map Backgrounds and Terrain

This task allows you to import and download background imagery and terrain to your site.

Map Backgrounds

	Import a georeferenced image	For importing image files that contain georeferenced meta-data (i.e. they have a location and area). They will be placed in the correct location on the map
	Import and rectify any image	For importing image files that do not contain any georeferenced information (i.e. a simple .jpg or .png file). The rectification tool appears to allow you to position the image on the map (see below).
	Download imagery	Download imagery from Bing Maps online sources (aerial and roads).

Rectification Tool

This tool allows you use a non-georeferenced image as a background image on the map. This is useful if you receive an image or PDF of the site layout that doesn't have any geographic reference. You can then use this rectified site layout image to help you lay out an existing site layout.

The idea is to add control points to the source image and add corresponding control points on the map (which will have a geographic position) using the downloaded background imagery as a reference. The software then warps (rectifies) the bitmap image by lining up the corresponding control points and stores the warped image as a background image.

To use it:

Open a source bitmap image. This appears on the top-left of the tool window.
Pan and zoom the workbook map (on the top-right of the tool window) to roughly show the same area covered by the source bitmap.
Right-click on the source image to add a control point. A corresponding control point appears in the workbook map.
Select and drag the corresponding point in the workbook map to the correct geographic location.
Add at least 3 controls points to help get the rectification correct.
Click the 'Rectify' button.

The image will be rectified and added as a background image to the map.

Terrain

You can import terrain files if you already have them, or download free terrain files for the area of your site.

Building regions (see Building regions below) also act as terrain, allowing you to add layout regions on top of them.

	Import a terrain file	If you have been provided with a specific elevation file for your site you can import it here.
	Download terrain	This shows the download wizard where you can download free SRTM (Shuttle Radar Topography Mission) terrain for the selected area. This is generally lower resolution than bought terrain files for your area, but often sufficient.

SolarFarmer supports terrain data in the following file formats:

File type	Accepted file extensions
Common elevation formats	.dtm; .grd; .xyz; .tif; .shp; .map; .hgt; .zip
DTM files	*.dtm
Surfer grid files	*.grd
XYZ files	*.xyz
Vector format files	.000; .DWG; .MP; .NTF; .asc; .bln; .cdo; .csv; .dat; .dgn; .dxf; .e00; .e57; .gm?; .gpx; .gtm; .gz; .kml; .kmz; .las; .laz; .ldb; .mif; .opt; .ovr; .plt; .rte; .shp; .tab; .tgz; .trk; .txt; .usr; .wpt; .xyz; .zip; catd.ddt; arc.adf; dht; lab.adf; lht
Elevation files	.1; .2; .NFT; .agr; .asc; .bil; .bip; .bln; .bsq; .bt; .csv; .dat; .dem; .dt?; .dte; .e00; .e57; .ers; .flt; .gm?; .grd; .gsd; .gxf; .gz; .hdf; .hgt; .img; .las; .laz; .ldb; .ter; .tgz; .tif; .txt; .xyz; .zip; *_fp; catd.ddt; demfloat; w001001.adf

Downloading terrain from within SolarFarmer

There are two terrain download options:

Terrain download options

SRTM terrain - low res (3 arc-sec). This is the default and is usually sufficient for most people.
SRTM terrain - high res (1 arc-sec). This is higher resolution terrain (if available for the area of your site).
The file sizes are much bigger and can make your workbook file size very large, so only use this option if you really need the higher resolution.

Note

The server used to retrieve the terrain has variable speed and reliability, so please have patience.

Manually downloading terrain

You can choose to manually download terrain files from the USGS servers (that the SRTM terrain files are stored on). This way you could create your own repository of terrain files to use in different workbooks, which may be quicker and easier to import into SolarFarmer than downloading them for each workbook.

To manually download your own terrain files:

Go to https://earthexplorer.usgs.gov and log in (create a free account if you don't already have one (required to download files))
Locate your site using the map or co-ordinates
In the Search Criteria Tab select Circle and put a radius of 30km (recommended if you want SolarFarmer to generate the horizon file, else can choose a polygon or circle at a radius of your choice) and press apply, you should then be able to see it on the map.
Go to 'Data Sets' tab and select:
- 'Digital Elevation' -> 'SRTM' -> 'SRTM Void Filled' for the lower resolution 3 arc-sec data.
- 'Digital Elevation' -> 'SRTM' -> 'SRTM 1 Arc-Second Global' for the higher resolution 1 arc-sec data.
Go to 'Results' and for each tile presented, use 'Download Options', you can use the BIL, DTED or GeoTIFF formats, but BIL is recommended for size of file.
Once the zip files are downloaded, import them into SolarFarmer using the Import Terrain File button above in the Setup Site Chapter, and the Map background/terrain task. You do not need to extract the archives, you can just select the ZIP files all at once. You may get a message saying "The data and workbook projections are different. Would you like to reproject the data or cancel?" Select OK, this prompt will come up for each file being imported.

Please note that this does download a large amount of terrain and can make the workbook quite large, once you have generated a horizon file you can choose to delete tile co-ordinates you no longer need.