colored topo maps

[keba 0]

?

[Tesselator 0]

bump bump...

 

I read someone liked the formula for figuring out a slope in degrees but I didn't see the formula anywhere in the thread. Hmmm Skimming too much?

 

With data from just about any topo map (including Google Earth!):

 

You can get the altitude at any two points of interest and the distance between them. From there it's easy to figure out the Slope, the Grade, and the Angle (from level).

 

Let's draw it out to make it simple.

 

Make a right triangle where the two altitudes "points" (A and C) form the hypotenuse and the distance is the base (Line BC). The height (Line AB) is just the two altitudes subtracted.

 

Like so:

 

 

 

To get the Slope:

Divide the Height by the Distance.

for example 400 meter Height and Distance 1500 meters would be 400/1500. The result of this division is called the "Slope".

In this case Slope=0.2667 because 400/1500=0.2667

 

To get the Grade:

Just multiply the Slope times 100. A "Grade" is a percentage. So our example here would be a 26.67% Grade.

 

To get the Angle:

We actually need trig. {gasp!} But most calculators have what we need here - just inverse tangent. On your calculator it may be called tan-1, or arctan or Atan.

Just enter the "Slope" and press Atan (or whatever it's called on your calculator) and it will give you the Angle C in degrees.

In our example atan(0.2667)=14.93 So the Angle C is 14.93 degrees.

 

Pretty easy huh?

 

 

--

Also I would like to point out that "0.9 of a life" is called a concussion. 0.5 of a life is commonly known as crippled and etc.

[tsondaboy 0]

PS: Just be careful when you take your readings from a photocopied map or a print out. The photocopy tends to be shrunk a bit, which means that the horizontal distance has changed! Refer to the sidebar scale (since it will have shrunk the same amount as the map) to estimate the horizontal distance.

 

I think I saw some compass/ruler/map angle estimation gadget that had markings on it for the 30,45,60 deg angles to be used on a 1:25000 topo map.

[Tesselator 0]

Hey that sounds like a neat gadget!

[keba 0]

Tess, db le p used it as his signature for a while, so it wasn't in the thread as such. He posted it in another thread (can't remember which one), along with a way to plug the equation into excel to do the number-crunching automatically for you. It's been so long since I used a scientific calculator, I clean forgot about tan-1. Thanks for the refresher.

[quattro 1]

i came upon some decent mapping software that allows to do 3D maps. There is a program at the bookstore called Kashmir 3D . It's in Japaneses and includes the maps 2600 yen. If you go to there web site you can down load a free English version.

 

To get it to work in English had to load the Japanese version then the maps. Then loaded the English version.

 

Pros: decent 3d graphics of maps, can track GPS routes on the maps. relatively inexpensive.

 

Cons: Some of the map data is a little out of date. The contour interval could be better 20M wish it was 10M

 

examples can be found here. examples

[tsondaboy 0]

More on kashmir here:

http://www.snowjapanforums.com/cgi-bin/ultimatebb.cgi/topic/5/55.html?

[quattro 1]

Thanks tsonda

[keba 0]

That looks pretty cool, I'll give it a run.

[Tesselator 0]

Nice. It's a damn shame there's no Mac UB version!

[tsondaboy 0]

Something I forgot to mention.

Once you access online through Kashmir some of the GSJ 1:25000 topo-maps, you can view them even when not connected to the internet. They are automatically saved in your computer.

Unfortunately you cannot open any other parts because it saves only areas you have already opened and not for all Japan.

If you have patience, you can slowly scan bigger parts on line so that you have a database to work even when you don’t have internet access.

[SerreChe 2]

Has anybody tried to overlay some map images over DEMs and create some MAT files in Kashmir? I have tried to do that with GSI 1/25000 & DEM 50m, and the result look kinda of funny (rivers running accross mountain tops, etc...). Basically the bmp map does not seem to align with the DEM properly when overlaid. I was very careful with the coordinates when creating the BMP overlay. I am just wondering of it is a Kashmir bug or whether it is a SerreChe bug.

[tsondaboy 0]

Is the elipsoid system of the DEMs (aka WGS 84, Tokyo etc) you use the same as the elipsoid you use to view your maps on kashmir?

[SerreChe 2]

Probably not Tsonda. You are really the Kashmir guru. Looks like a SC bug after all, let me try it again. Thanks.

[SerreChe 2]

Apparently there's also an addin that can be downloaded that can make the stiching of 1/25000 GSI maps a lot easier. There so much stuff in the download page, I am not sure which link it is. I did mine by hand... Now that's art!

[tsondaboy 0]

Probably you are talking about this plugin

http://www.kashmir3d.com/download/kashmir_digitalmap.cgi

[SerreChe 2]

I have tried to match SouthWest base for both the BMP and DEM and still have the same problem.

Hmmm, still gotta do some more digging.

 

Thanks for the link, I'll have a look at it.

[tsondaboy 0]

Dont worry, its something I used to mistake in the past too. It kind of confusing in the begining, I will try to post some examples tomorow.

 

Here is some info you might find usefull for the time being.

http://en.wikipedia.org/wiki/Geodetic_system

Dont bother with the equations and staff, just try to understand the diferences between the systems.

[soubriquet 0]

SerreChe. I've draped some topo maps over the 50 metre DEM. I've done it using ENVI, which is the professional weapon of choice for this kind of raster work.

 

Basically, they never fit, although you can get a reasonable approximation. That is because both data sets are approximations, and contain errors. This is Shibutsu. The fit looks quite good but some rivers and ridges can't be made to fit properly.

 

[tsondaboy 0]

Is this what you are trying to make big guy?

 

[SerreChe 2]

Thanks Tsonda, it all kinda makes sense now.

 

Soub, that Drapped DEM is a thing of Beauty!!!

Wow, that's exactly what I have been trying to do with Kashmir, but it looks like it's gonna be difficult. Just curious, why can ENVY do it and Kashmir cannot? Does ENVY have some kind of conversion algo or something?

[tsondaboy 0]

SerreChe, that pick is made with Kashmir.

 

If you have time, bring your laptop at my place and will give you some MEMs and instructions how to use them with kshmir.

[soubriquet 0]

ENVI has a warp function to fit one image over another, but I've never managed to get it to work. At the CSIRO we used an in-house utility which worked very well, but I no longer have it.

 

The fit is down to trimming and stretching the topo map line by line. ENVI Has a great toolbox for this, but it is only about 1% of the functionality.

 

ENVI has been written as a collective effort by and for the scientists working with remotely sensed data. That includes aerial photography and satellite data. I used it to average the sst data for the January Temperature thread. I wrote a simple band math routine to average six years of R,G & B data and build them into a new image.

 

Historically, topo maps were made by projecting stereo photo pairs in red and green onto a plane table. The operator, wearing glasses with one red lens and one green lens would manouevre the table by the required contour interval, and trace the contours around the zone in focus. This is a subjective process and entirely dependent on the technician's ability to stay focussed. This is what I did in the army. I'll stand by my maps, but they are only an approximation.

[SerreChe 2]

Tsonda, how on earth did you manage that?

I have the MEMs (553826,27,16,17).

So how did you do it?

 

Soub, that red & green business sounds complicated but interesting. Before I had never realized that maps could a bit subjective. If you made a faulty map in the past by mistake can they come after you?

[tsondaboy 0]

You have to first open the GSI topo maps and locate the area you want to create a 3D topo/relief image.

Once you do that go to 編集 and locate the option 標高データを重なる（MATの作成）on the window that pops up press 次へ　and on the next tab use the 参照 button and locate the MEMs/DEMs.

That should probably overlay the topo maps over the relief map.

Next open カシバード and on the カメラ panel locate the longest bar and select one of the 地図との合成　options.

That should do the trick.

Good luck!