Google Maps Terrain Downloader support

How to download google maps terrain images

Some problems when downloading

How to view downloaded terrain maps

How to combine small terrain images into one big terrain image

How to know the longitude and latitude of each image

How to download Google Maps terrain images?

See the screenshot. It is very easy to use.

Firstly, enter a project name, such like "example.gmtd". All project files are saved as *.gmtd. If you want to continue a old project, click button "Open project".

There are 4 parameters (Left Longitude, Right Longitude, Top Latitude, Bottom Latitude) to define the area scope of images that you want to download.

The zoom parameter define the image precision.

And you can define how many threads you want to start to download at the same time.

Select a path to save the project and downloaded images, then click button "Download", OK, start downloading now ... !

When downloading, the log window will display the downloading process. When finished, the log will be saved to a file.

Parameters explainment:

1. Left Longitude: -180<value<180, for East, the value is positive, for West, the value is negative.
2. Right Longitude:-180<value<180, for East, the value is positive, for West, the value is negative.
3. Top Latitude:-90<value<90,for North, the value is positive,for South, the value is negative.
4. Bottom Latitude:-90<value<90,for North, the value is positive,for South, the value is negative.
5. Zoom: defines the image precision, the max zoom level is 15. (For trial version, the min zoom is 10)
6: Threads number: defines how many threads you want to use to download at the same time. The max threads number is 8.

For longitude and latitude, the input measurement is degree. You can convert the measurement of "Degrees, Minutes,Seconds" to "Degrees" by click menu
"Tools->Convert 'Degrees,Minutes,Seconds' to 'Degrees'...".

How to get the lat/long info from Google Maps?
On Google Maps, You can right-click a location on the map and select "What's here?" The coordinates of that location will automatically appear in the Search box at the top of the page.

Some problems:

1. Google maps uses a protection mechanism to keep a good quality of service. If one makes too much requests, google map will add its IP address to a blacklist, and you may see a message:

403 forbidden

If this happend, Google Maps Terrain Downloader will show a messge in log window: May be your IP is banned by Google. Then you must wait for some time or change to another IP.

2. For some area, there are not high precision images on google's server, so may be caused a error when you try to download such images. If this happend, you need to set smaller zoom level to download. (The max zoom level is 15)

How to view downloaded terrain map images?

You can view downloaded terrain map without combining them into one big BMP.
We provide a tool : You can run it from menu "Tools"->"Terrain Map Viewer".

Then open a project from menu "File"->"Open project..." to view the map.

How to combine small images into one big image?

After downloading, all small images are saved on your disk. Then you can combine them into one big image map.

We provide a tool : You can run it from menu "Tools"->"Combine images... ".

The output big image is in BMP format. You can convert it to other format by yourself using some image tools such like PhotoShop.

How to know the longitude and latitude of each image

There are two methods to know the longitude and latitude of every downloaded image.

1. After downloading, the software will create a text file named as "projectname_list.txt" in your project path. In this file all the images' longigude and latitude information are saved.

The file looks like:

ImageFileName left_Longitude top_Latitude righ_Longitude bottom_Latitude
t_840_382.png: 115.31250000000000 41.50857729396144 115.66406250000000 41.24477233961692
t_840_383.png: 115.31250000000000 41.24477233961692 115.66406250000000 40.97989806616793
t_840_384.png: 115.31250000000000 40.97989806616793 115.66406250000000 40.71395582284703
t_840_385.png: 115.31250000000000 40.71395582284703 115.66406250000000 40.44694705617491
t_840_386.png: 115.31250000000000 40.44694705617491 115.66406250000000 40.17887331093505
t_840_387.png: 115.31250000000000 40.17887331093505 115.66406250000000 39.90973623113918

2. When you view map in Map Viewer, the longitude and latitude will be displayed in the statusbar.

And in the log file, the exactly longitude and latitude of the downloaded area are saved as Left Longitude download.., etc.. see the followed example.

An example of log file:

Project: C:\Downloads\beijing_10.gmtd
Log begin...
Now time is:2010-9-5 21:07:05

Left Longitude input= 115.5
Right Longitude input= 117.5
Top Latitude input= 41.3
Bottom Latitude input= 39.2

MinX = 840
MinY = 382
MaxX = 846
MaxY = 390

Left Longitude download=115.3125
Right Longitude download=117.7734375
Top Latitude download=41.5085772939614
Bottom Latitude download=39.0959629329506

All images scope information are saved to C:\Downloads\beijing_10_gmtd_list.txt

Total count of images would be downloaded: 63

Download threads count: 8

Zoom level: 10

path: C:\Downloads\

Start downloading...
--------------------------------
Thread4:seq=3, file=t_840_384.png ->ok!
Thread6:seq=5, file=t_840_386.png ->ok!
Thread1:seq=8, file=t_840_389.png ->ok!
Thread5:seq=4, file=t_840_385.png ->ok!
Thread2:seq=1, file=t_840_382.png ->ok!
Thread7:seq=6, file=t_840_387.png ->ok!
Thread3:seq=2, file=t_840_383.png ->ok!
Thread8:seq=7, file=t_840_388.png ->ok!
Thread6:seq=13, file=t_841_385.png ->ok!
Thread2:seq=9, file=t_840_390.png ->ok!
Thread7:seq=14, file=t_841_386.png ->ok!
Thread4:seq=11, file=t_841_383.png ->ok!
Thread3:seq=10, file=t_841_382.png ->ok!
Thread1:seq=16, file=t_841_388.png ->ok!
Thread8:seq=15, file=t_841_387.png ->ok!
Thread2:seq=17, file=t_841_389.png ->ok!
Thread6:seq=21, file=t_842_384.png ->ok!
Thread3:seq=18, file=t_841_390.png ->ok!
Thread7:seq=22, file=t_842_385.png ->ok!
Thread1:seq=24, file=t_842_387.png ->ok!
Thread4:seq=19, file=t_842_382.png ->ok!
Thread8:seq=23, file=t_842_386.png ->ok!
Thread3:seq=26, file=t_842_389.png ->ok!
Thread2:seq=25, file=t_842_388.png ->ok!
Thread4:seq=27, file=t_842_390.png ->ok!
Thread6:seq=29, file=t_843_383.png ->ok!
Thread1:seq=32, file=t_843_386.png ->ok!
Thread7:seq=30, file=t_843_384.png ->ok!
Thread8:seq=31, file=t_843_385.png ->ok!
Thread3:seq=34, file=t_843_388.png ->ok!
Thread4:seq=35, file=t_843_389.png ->ok!
Thread2:seq=33, file=t_843_387.png ->ok!
Thread6:seq=37, file=t_844_382.png ->ok!
Thread1:seq=40, file=t_844_385.png ->ok!
Thread7:seq=38, file=t_844_383.png ->ok!
Thread3:seq=42, file=t_844_387.png ->ok!
Thread4:seq=43, file=t_844_388.png ->ok!
Thread8:seq=39, file=t_844_384.png ->ok!
Thread2:seq=41, file=t_844_386.png ->ok!
Thread6:seq=45, file=t_844_390.png ->ok!
Thread1:seq=48, file=t_845_384.png ->ok!
Thread4:seq=51, file=t_845_387.png ->ok!
Thread3:seq=50, file=t_845_386.png ->ok!
Thread7:seq=46, file=t_845_382.png ->ok!
Thread6:seq=53, file=t_845_389.png ->ok!
Thread2:seq=49, file=t_845_385.png ->ok!
Thread8:seq=47, file=t_845_383.png ->ok!
Thread1:seq=56, file=t_846_383.png ->ok!
Thread1 Finished.
Thread6:seq=61, file=t_846_388.png ->ok!
Thread6 Finished.
Thread7:seq=54, file=t_845_390.png ->ok!
Thread4:seq=59, file=t_846_386.png ->ok!
Thread4 Finished.
Thread3:seq=58, file=t_846_385.png ->ok!
Thread3 Finished.
Thread8:seq=55, file=t_846_382.png ->ok!
Thread2:seq=57, file=t_846_384.png ->ok!
Thread2 Finished.
Thread7:seq=62, file=t_846_389.png ->ok!
Thread7 Finished.
Thread8:seq=63, file=t_846_390.png ->ok!
Thread8 Finished.
Thread5:seq=12, file=t_841_384.png ->ok!
Thread5:seq=20, file=t_842_383.png ->ok!
Thread5:seq=28, file=t_843_382.png ->ok!
Thread5:seq=36, file=t_843_390.png ->ok!
Thread5:seq=44, file=t_844_389.png ->ok!
Thread5:seq=52, file=t_845_388.png ->ok!
Thread5:seq=60, file=t_846_387.png ->ok!
Thread5 Finished.

--------------------------------
Download Finished.

Now time is:2010-9-5 21:07:31

Log file has been saved to C:\Downloads\beijing_10_gmtd_log.txt