Detailed Terrain Relief

[pagsab]

As in some other SF2 terrains, the amended tilesets which I have made for my own personal use have until now eschewed the tiny heightmap files which add detailed relief to coasts and river banks.  However, at the end of my previous long thread at https://combatace.com/forums/topic/101404-spain-and-seaplanes/, Gerwin recommended the heightmap files as a way of handling islands too small for the blunter instrument of elevation points in the HFD.  After studying his Iceland terrain, I at last worked out that these heightmap files overlay extra terrain height on top of that specified in the HFD, at 256 elevation points per tile instead of the standard 16.  My usual blundering experimentation finally let me create a bespoke heightmap file for my smallest island as shown below, which takes up only a quarter of a tile on my reduced scale terrain.  As suggested by Gerwin, I removed my previous single elevation point whose blunderbuss effect had inevitably made some coastal water slope disconcertingly upward along with the land, and instead I relied entirely on my new and much more precise grayscale heightmap bitmap which added extra height in proportion to the lightness of each pixel.  Since elevations are always applied to the SW corner of each box just as in the HFD, I needed to test my heightmap with the tile in all four possible orientations, and remove any elevations which raised water as well as land.  I gave my various single tile islands a generic gentle slope by setting their HeightMapScales at 50 in the terrain data.ini, but I created separate steeper variants of the uncultivated islands by using a setting of 150 (as seen below from a Macchi 200 over tiny Panarea in the Lipari isles of my new Sicily and Malta terrain).  Beyond 150, the unwelcome side-effect of the sagging of the tile below sea level for reasons I do not understand becomes too noticeable to be tolerated.

 I was delighted to find that I could also in due course use this heightmap technique to make the chalk cliffs in my NW Europe terrain steeper, by reducing their horizontal width from a quarter to a sixteenth of a tile.  However, what really excited me about the heightmap files was not their utility in a few niche cases but rather their potential to make my terrain relief as a whole look less jagged and more natural.  I created a generic 'noise' heightmap file as shown below, designing it so that the pattern would be unaffected by tile rotation and so that it would be easy to black out one or more of the four elements to tailor the heightmap for coastal as well as inland use.  Having assigned all my tiles except those with airfields, rivers or built up areas an appropriate variant of this generic heightmap file, I fired up the sim with some trepidation, fearing that using this technique so widely would drastically reduce frame rates.  To my great relief, the only obvious adverse impact was a thin shifting white line in the distance marking the limit at which the system incorporated the heightmaps – a bit distracting, but by no means a showstopper.  The compensatory payoff was an incredibly rich and rolling topography, especially in areas like the mountains on either side of the Straits of Messina as shown by the low flying SM.79 below.  I could not resist the sheer enjoyment of weaving at treetop height through the maze of winding valleys which my rescaled HFD data and my high resolution generic heightmaps had combined to create.

This technique is fairly quick and straightforward and can be used on pretty much any SF2 terrain, whether it already uses heightmap files or not.  It is especially worthwhile in terrains with 16 rather than 64 elevation points per tile.  I will now give a short step by step guide to how to apply it to inland tiles, based on my own recent experience.

 

-        Copy from this or another terrain two 16 pixel square heightmap bitmaps – one all black from a sea tile and one with a range of grayscale shades from black to white.

-        Open the two bitmaps side by side in Photoshop, and expand them greatly as shown above. (I tried using GIMP or Microsoft Paint instead, but only with my old copy of Photoshop could I get my amendments to the indexed bitmap to work properly.)

-        Pick up a shade from the second bitmap and paint it onto the first using a single pixel brush. Continue to create your desired generic noise template from dark grey to white.  Just a few appropriately spaced shades will suffice, and you can pick up black to roll back if need be.  EDIT: Make the background of your bitmap dark grey rather than black, for reasons discussed in my exchanges with Gerwin later in this thread.

-        When you are happy, save your creation as an 8 bit bitmap, and paste a copy into your terrain folder.  Different tiles can reference the same bitmap, but this only works if they use the same HeightMapScale.  You need to save the bitmap again with a different name for each different HeightMap Scale you wish to use.

-        Open your terrain's data.ini, and scroll down to the first inland tile texture which you wish to use this bitmap.  Add 'HeightMap=XXX.bmp' and 'HeightMapScale=XX.000000', substituting the file name you have given the bitmap and the value you wish to assign.  I find that 25 for field tiles and 50 for hill and wood tiles gives a good result.

-        Continue adding similar entries to all inland tiles which you wish to use your new bitmaps.  I recommend deleting any existing heightmap entry from the all sea tiles, where it seems rather redundant.  When you are done, close the data.ini and opt to save your changes.

-        Start the sim, create a flight, and explore to see the result.  Go back and tweak the noise bitmaps or HeightMapScales based on what you find.

 

I hope that these ideas may help others to enjoy their own preferred SF2 terrains even more.  I am very grateful to Wrench and Gerwin for highlighting the utility of these tiny but potentially very helpful heightmap files.  If anyone has any ideas of how to remedy the tile sagging or white line side-effects which I mentioned, do please let me know. 

 

Edited November 4 by pagsab

[Gepard]

IIRC had the modification of the _hm file the issues, that you can fly through the hills and that groundobjects "sink" into the soil.

[gerwin]

In my IcelandNA example: The plain sea also has a _HM. And the _HM shows a certain zero level of gray for sea level. Gray, not Black. 25% of black, or 64 out of 255 in rgb terms. I had good reasons to do so back then, altough the particulars escaped me. 

May have some interactions with terrain _data.ini settings as well, like the ones below.

[HeightField]
DetailScale=1.0
DetailFrequency=1.0
MaxHeight=200
MinHeight=0

[HeightOffset]
NonTexturedMesh=-10.0
TexturedMesh=-5.0
DetailedMesh=0.0
LowDetailMesh=-1.0
;WaterMesh=0.8
WaterMesh=0.1
 

[pagsab]

Thanks for your thoughts.  My trees and buildings seem to fit my hybrid ground surface well, and my plane does so also if I taxi off the airfield, so hopefully the system does recognise the graphical appearance as real.  I tried shifting to Gerwin's general height settings during my initial troubleshooting, without apparent effect.  I also tried giving sea tiles their own heightmaps, but all this seemed to do was to extend the white line problem onto the sea where it is even more noticeable.  However, I just tried Gerwin's idea of making the background of my small island heightmaps dark grey instead of black, and to my delight this stopped the sagging even when I dialled the HeightMapScale up to 300.  There was no problem at the tile borders with sea tiles lacking their own heightmaps.  I recommend that others try Gerwin's suggestion if experimenting with heightmaps for themselves.    

[pagsab]

Today has been such a lucky day!  The specialist used book which I ordered 2 months ago from Madrid on seaplanes in the Spanish Civil War turned up at last when I had almost given it up for lost.  Not only that, but when I fired up my CR-42 after changing the background of my island and inland heightmaps from black to dark grey, I was amazed to see that, instead of snaking distractingly across Etna, the white line was confined to the distant coast.  I have no doubt that when I repaint the background of my various coastal heightmaps, the line will disappear from there too.  Gerwin's simple trick has solved both adverse side-effects of my heightmap initiative at a stroke!  We owe him so much.  His TFD editor is utterly invaluable for SF2 terrain creation, and now his heightmap suggestions have unexpectedly given me the biggest improvement to my SF2 experience since I discovered how to fly as a wingman.  Thank you Gerwin.  You are the patron saint of SF2 terrain makers! 

[pagsab]

A classic biplane at my fingertips, rugged hills rolling away just below, puffy clouds in the afternoon sunshine, my airfield securely visible on the coast, and Etna brooding in the distance without a white line in sight.  Sheer bliss!

[pagsab]

The one remaining downside of heightmap files is that the elevation they create on a given tile type can be varied only by making distinct copies of the tile concerned.  Now that Gerwin's trick has solved the tile sagging problem, I have boosted the HeightMapScale of the steep variants of my single tile islands to 200 or 250, to show volcanic isles like Stromboli.  Conversely, I have created some separate versions of my scrubland tiles with no heightmaps at all, to represent fens, dry lakebeds or flatter terrain like that on Malta.  Since I still lack the expertise to edit or create LOD files, I have used similar tile variants to make concrete runways, by painting onto my small grass airfields a typical generic pattern of crossed runways and perimeter track as shown below at Catania SE of Etna.  This looks fine even when taking off or when taxying the short distance to the hangars after landing.  My deliberately compact initial tileset of just 54 different tiles has expanded to 63 as a consequence, but it is worth it to gain the extra representational flexibility.  I had to take an enforced break from my SF2 modding yesterday when a truck brought down power cables and cut our electricity for 12 hours, but having to go to bed at sunset instead of after midnight probably did me good...

 

[pagsab]

As shown below, I just finished modelling Sicily and the surrounding islands, giving me the same size 90 by 64 tile MTO terrain as that I created earlier for the Spanish coast.  Each of these reduced scale terrains represents 150,000 square kilometres, because each tile models an area 5.1 km across.  Both terrains are ready to be expanded further, but I will probably return to my NW Europe project first so as to create a similar 90 by 64 tile terrain stretching across the North Sea from London to Holland, with each tile representing only 3.3 km due to the denser concentration of airfields and urban areas than in the Mediterranean.  I have already trialled the incorporation of rescaled HFD data and of heightmap files in my test vignette of the Isle of Man, and these advances work just as well there as in Italy and Spain.  When the full first stage of NW Europe is ready, I can make the WW1 variant which will let Gothas fly from Ghent to London while British fighters from Dunkirk and the UK struggle to intercept, sometimes crossing the Channel themselves during their sorties as happened in reality.  Creating these reduced scale terrains remains difficult and time-consuming despite the new techniques I have developed, but the payoff in having a beautiful backdrop for a growing range of complete historical combat missions makes the effort well worthwhile.

   

[pagsab]

Before moving on, I am enjoying further scenic flights over Sicily, now using my wingman trick which first sparked my revived interest in the Third Wire sims.  The picture below shows our flight of Macchi M.41 flying boat fighters (which I converted from Stephen1918's static M.5 in the Caporetto terrain) passing Palermo during a morning patrol in 1937 from the Stagnone lagoon along the mountainous north coast of the island and down through the straits to the other main seaplane base at Augusta.

[TomSnug]

Very nice work on all of this! It is a pity we can't actually do water take-offs in this sim.

 

[TomSnug]

How good would this be, if we could do water take-offs:

[pagsab]

See my https://combatace.com/forums/topic/101404-spain-and-seaplanes/ thread for how I have tweaked data.inis to let seaplanes take off and land after all, albeit by accepting an Easy setting for landing.  The air cushion is a bit distracting from a water level external view, as is the lack of spray, but even AI planes can operate from the water, including my 'Frankenstein' static models.  As usual, others also solved this problem before - see for instance Stephen1918's North Sea add-on for FE2.

 

Edited Saturday at 07:37 PM by pagsab

[TomSnug]

Thanks, I will check that out.

 

[pagsab]

Here is a nice shot of our M.41 flight landing together at Augusta.  For some reason, AI-flown versions of this particular seaplane mash-up currently generate a cloud of smoke on landing, which would be a welcome stand-in for water spray if they didn't usually spoil it by exploding - even more disconcerting than the standard AI behaviour of vanishing into thin air after landing!  My own plane, seen here on the right, lands perfectly safely and can be taxied back across the water to park alongside the static Z.506 Heron in front of the hangars.

[TomSnug]

Nice one!

Does this mean that aircraft with wheels can also land there?

[pagsab]

Anachronistically, wheeled planes can operate even better than seaplanes from such water bases, and seaplanes can operate better from land bases than from water bases!  I have now posted at the end of my long Spain and seaplanes thread a comprehensive survey of the ways I have found to make seaplane operations better.  The solution to the problem of AI landing damage as shown in the picture above was simply to raise the models a little more above the water than I had done already.

[Wrench]

and don't forget to adjust the hit boxes and collision points!