How to raise Airport elevation?

[Gray_Lensman]

Using the stock FSX Madeira (LPMA) airport as a test. This airport is one of those up on a plateau around 711 ft. I'm trying to correct it to approx. 143 ft as per the charts.

Using the Change Airport Altitude tool, I set the altitude to 143.00. I also created a Flatten polygon around the perimeter of the airport background and also set it to 143.00. Once installed into the \Addon Scenery\... folder I got this image for a result.

http://www.mediafire.com/view/?2e8j9amdlnlaj5q

Can anyone help this newbie to understand what is going wrong?

Incidentally. the altitude in the trike is pretty close to my desired setting, but as you can see, I have some, shall we say, junkie looking artifacts outside AND within the boundaries of what I thought was my flatten polygon.

Regards

 

[rfields]

Some background first.

If you use SHFT+Z the elevation you see for the trike is not the airport elevation. It is the eyepoint elevation above the ground contacts point as set by the aircraft.cfg file.

FS uses the airport altitude in the FIRST file it reads for an airport. So the ADE Change Airport Altitude tool creates what we call a stub-airport file in the Scenery\World\Scenery folder which contains only the new airport elevation.

Another item is that airports are made up of several elements. One of those is the airport background polygon.

You need to exclude the original airport background polygon, and create a new background polygon which ADE will set to the airport elevation you are using at the time you create that polygon.

You should not use a flatten for this, but Flatten Mask Class Map ExcludeAutoGen polygon.

Not excluding the default airport background polygon could cause some of the effects you are seeing.

But at many of the bad altitude airports in FSX, you are going to have to create some extra polygons around the airport to 'even out' the terrain spikes from the terrain mesh. This can take some testing to get right.

You might have to create some extra polygons, triangle shape works best, with different elevations set for each vertex point.

 

[Gray_Lensman]

Some background first.

If you use SHFT+Z the elevation you see for the trike is not the airport elevation. It is the eyepoint elevation above the ground contacts point as set by the aircraft.cfg file.

True. I'm seeing 149, but I already knew that and assumed the runway below was properly set to 143'.

FS uses the airport altitude in the FIRST file it reads for an airport. So the ADE Change Airport Altitude tool creates what we call a stub-airport file in the Scenery\World\Scenery folder which contains only the new airport elevation.

Okay, I've seen that file and assumed that's exactly what it did.

Another item is that airports are made up of several elements. One of those is the airport background polygon.

You need to exclude the original airport background polygon, and create a new background polygon which ADE will set to the airport elevation you are using at the time you create that polygon.

You should not use a flatten for this, but Flatten Mask Class Map ExcludeAutoGen polygon.

Not excluding the default airport background polygon could cause some of the effects you are seeing.

So, I removed the flatten polygon and used the Flatten Mask Class Map ExcludeAutoGen polygon. Am I understanding correctly that this polygon not only performs the flatten function but the exclude function as well? I get the same visual results using either by the way.

But at many of the bad altitude airports in FSX, you are going to have to create some extra polygons around the airport to 'even out' the terrain spikes from the terrain mesh. This can take some testing to get right.

You might have to create some extra polygons, triangle shape works best, with different elevations set for each vertex point.

I'm thinking this is probably the root cause of the terrain "spikes" I'm seeing, but being a newbie, this has got me stumped because I see the "spikes" within AND outside of my airport background polygon. I would have thought the use of the Flatten Mask Class Map ExcludeAutoGen polygon would take care of issues within its boundaries. So what am I missing?

Thanks for the help.

Regards.

 

[rfields]

So, I removed the flatten polygon and used the Flatten Mask Class Map ExcludeAutoGen polygon. Am I understanding correctly that this polygon not only performs the flatten function but the exclude function as well? I get the same visual results using either by the way.

You need one small polygon on the airport, but not over the airport reference point, to exclude the default background polygon. This polygon needs to be Type "Exclude Specific" and Tag "Airport Backgrounds Flatten MapClassMap Autogen"

You need a new polygon - the Flatten Mask Class Map ExcludeAutoGen one you created for the new, lower, airport background.

Your on-airport terrain spikes might be due to two active background polygons.

The first small polygon - I use about 100 x 100 ft - keeps the 710.997 ft elevation background from influencing your airport.

The second big polygon you create is the new airport background at 143 feet.

I always make the second new background polygon a bit larger than the original airport background to help minimize the spiking.

I'm thinking this is probably the root cause of the terrain "spikes" I'm seeing, but being a newbie, this has got me stumped because I see the "spikes" within AND outside of my airport background polygon. I would have thought the use of the Flatten Mask Class Map ExcludeAutoGen polygon would take care of issues within its boundaries. So what am I missing?

The terrain spikes can come from a few sources, but most of them are caused by where a terrain mesh elevation point is not covered by the new polygon. Sometimes these are so close to the edge of the airport polygon, we don't see them until you get the airport put together. The terrain on the waterside of the airport will still be at elevations over 700 ft. You have to knock them down with landclass polygons.

At that point, I use FSX and ADE to mark the location of each individual spike and create a triangle landclass polygon to cover the spike.

Once the landclass polygons knock the terrain spikes down, I can then adjust the elevation of individual VERTEX of the triangle polygon to smooth out the airport to surround terrain blend.

 

[Gray_Lensman]

You need one small polygon on the airport, but not over the airport reference point, to exclude the default background polygon. This polygon needs to be Type "Exclude Specific" and Tag "Airport Backgrounds Flatten MapClassMap Autogen"

You need a new polygon - the Flatten Mask Class Map ExcludeAutoGen one you created for the new, lower, airport background.

Your on-airport terrain spikes might be due to two active background polygons.

The first small polygon - I use about 100 x 100 ft - keeps the 710.997 ft elevation background from influencing your airport.

The second big polygon you create is the new airport background at 143 feet.

I always make the second new background polygon a bit larger than the original airport background to help minimize the spiking.

Okay, so far... Here's my latest results

Here's a view from a quick flight: http://www.mediafire.com/view/?c8z96uz4x3u6b3z

and

Here's a topdown view: http://www.mediafire.com/view/?oor18p6wevv11mp

The terrain spikes can come from a few sources, but most of them are caused by where a terrain mesh elevation point is not covered by the new polygon. Sometimes these are so close to the edge of the airport polygon, we don't see them until you get the airport put together. The terrain on the waterside of the airport will still be at elevations over 700 ft. You have to knock them down with landclass polygons.

At that point, I use FSX and ADE to mark the location of each individual spike and create a triangle landclass polygon to cover the spike.

Once the landclass polygons knock the terrain spikes down, I can then adjust the elevation of individual VERTEX of the triangle polygon to smooth out the airport to surround terrain blend.

I can see I have 4 spikes. This is where I'm confused. I can understand the spikes OFF to the sides of the airport background, but why would I still have spikes within the bounds of the airport boundary after defining the first two polygons?

When "knocking" down the spikes, I assume you have to completely "cover" the offending spike? and do these have to be "knocked down" prior to defining the new airport background polygon?

edit> I created a landclass polygon to cover the small spike closest to the beach but it didn't "knock down" the spike at all, but rather just redefined the terrain. I did something wrong obviously, but what?
Also, is there a way to determine the landclass terrain already in place at the offending location instead of trying to guess with over dozens of choices?

Thanks tremendously for your help.

 

[rfields]

Also, is there a way to determine the landclass terrain already in place at the offending location instead of trying to guess with over dozens of choices?

ADE tells me that the default LPMA airport is in the 0502 folder in the APX43200.bgl file.

I used TMFViewer from the Terrain SDK. I select File -> Open and browse to the 0502 folder and open the cvx43200.bgl file.

I use the plus sign key and arrow keys to zoom in the airport background area.

Then I use TMFViewer to open the worldlc.bgl file in the \Base\Scenery folder.

TMFViewer now shows the land class used around the airport. There are two 'Tropical Degraded Forest' sections north and west of the airport. The sections closest to the airport boundary are 'Fields and Woody Savanna' and there is some 'Forest and Fields' next to the coast and across the north end of the airport.