Author Topic: Quick question about elevations  (Read 450 times)

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Offline wilycoyote

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Quick question about elevations
« on: April 19, 2020, 02:31:31 PM »
Okay I am just playing around making maps up for scenarios based on the small ACW action at Picketts Mill and am playing around with contours and elevations.  Specifically I want to have negative elevations for my rivers ie create river beds, what is the easiest method to get this done?

I tried the shaper tools but there is no facility to set a negative value

Trying to contour the normal areas beyond the river beds is too imprecise and very time consuming

Do I need to  set a base level say 10 for the general map and therefore the river beds could be set to 0 or something like, then apply the normal contours to the rest of the map?

In general terms for larger scale maps/battles this is not too important, butknowing this would be useful as a lot of the smaller ACW actions are often littered with small creeks who's banks proved a real obstacle in some battles for instance Chickamauga

Any advice would be appreciated

Offline Andy ONeill

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Re: Quick question about elevations
« Reply #1 on: April 20, 2020, 05:18:05 AM »
The good news is you have a number of options.

IMO, elevation is the trickiest thing to get right for any map.
Whilst writing this thing I was keen to try and make the map editor a realistic option for the variety of use cases I could imagine.
Which is why there are so many tools available - although that offers so many options it's perhaps rather confusing.

Did you take a look at the wikia?
There's also a bunch of stuff in the change log which I wrote as I worked on the editor.

My preference would be to use the google maps elevation api option.
Many developers used to abuse their api.
They no longer let you use their api totally free without any limits so this involves obtaining a key.
You need to register a credit card with google and add that to a txt file the app reads.
Use of Google's api is out of our control ( obviously ) but it's effectively free.
There is a cost per call but this is offset against an allowance of $200 a month which is almost certainly  going to more than cover you.

If that doesn't suit for whatever reason then you can consider a variety of other options.
Way back when I did the google integration I tried Waterloo first.
Which gave great results other than there's the "Lion's mound" to remove.
This is why the first shaper was the "flatten" tool.

Online there are various sources for elevation. These are usually presented as a coloured picture. You could grab one of these.
You'd probably need a bit of rotating and cropping.
The greyscale picture import will  convert even coloured pictures to greyscale.
Note that this is based on their tonal values - darker = lower.

The way our maps work is an artist draws a greyscale representation, blurs that and this is then converted.

If you already have something you've been working on then it's default level is probably 0.
You can't have negative elevations so you need to give it something to work with before you gouge any valleys out.
The shapers raise tool allows you to apply an additional value across the entire map.

Ridges can have a negative value, so you can apply a negative ridge shaper.
If you're trying to reproduce a specific piece of terrain and you want precision then I think you might find this rather difficult to work with.

The Custom shaper allows you to use a picture which can include transparent.
You could therefore draw just your valleys in greyscale and give that a go.

I recommend trying options out on a "scratch" experimental map before you try on one you already spent hours working on.
Always back your work up.

Offline wilycoyote

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Re: Quick question about elevations
« Reply #2 on: January 08, 2021, 02:57:47 PM »
Sorry it has been a long time replying but thanks for the advice andy.

I have tried Google maps with varying sucess and same same applies to grabbing pictures and using greyscale.

I returned to you rpost and considered what i wanted to do and was struck about  your comment about raising the map .  This was the key I was looking for and although not perfect has made me realise the power in these tools.  By raising the whole map to a higher default value of let us just say 25, I can now place counters with a value of 10, that when displayed give me the "valleys and gullies " I was looking for 

Offline Andy ONeill

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Re: Quick question about elevations
« Reply #3 on: January 11, 2021, 11:28:23 AM »
Great stuff.

There are three problems with the easy opion of google maps data.

Things might have changed - so you need to say carve freeways back out.
What they consider reasonable variation can introduce too much noise.
Period maps you see in books are often very inaccurate sketch maps and nigh on fantasy. So they are mutually exclusive with accurate data.

It's because Ezra prefers such maps for backgrounds, we can't use real world data.
There is maybe a half way house if you're prepared to hack up bits of a period sketch map and rebuild something to match real world