View Full Version : "Curves do not cross correctly" with Patch and points won't merge :(

07-06-2011, 05:33 PM
I'm following a tutorial from the essential Lightwave 9 book chapter 18 on building human head yeah.

The book says...

Select the outer loop anti clockwise and click PATCH etc, if you get error message saying "Curves do not cross correctly" then press M to merge points.

Well I got the first error and when I press M it just says "No points eliminated"

So im kinda stuck :S

Any suggestions, thanks :)

07-06-2011, 05:37 PM
Merge points is working with very close to each other points, which have exactly the same attributes like vmaps. If two or more points are farer than tolerance, then they won't merge. Watch your selection point count, on the left bottom slightly above Point/Edge/Polygon mode switchers. And use Weld Points instead.

If you want your spline modeling easier get EasySpline
it will automatically show you when you have proper spline patch, it will just show up, without having to selecting splines and running tool, as you can see on videos.

07-06-2011, 05:42 PM
Thanks mate here is a image of what I mean, maybe easier to see whats wrong...


07-06-2011, 06:15 PM
That should be rather obvious- your curves don't even have any points common each other...
Message was "Curves don't cross correctly".. your don't cross at all..

07-06-2011, 06:17 PM
Try something simple for beginning in spline modeling-
make array of 9 points (f.e. Box tool, segments 2,2,1 size 1,1,0), then remove polygons, leave points, and select top 3, make spline, select right 3, make spline, etc. with the rest.
That's what is called "splines connected properly"

07-07-2011, 12:20 AM
Made this for you, might help a little ...

07-07-2011, 03:06 AM
Ahh thanks people :D

Think I know why its not doing it now, I did above the eyebrow line and on the cheekbone then put the points either end but I must have splined them wrong thats why their not matching up, my fault for not reading the book properly lol.

Will re-try it then post results thanks again.

07-07-2011, 04:51 AM
Something more like this would work. You can see here 8 valid spline cages. Each cage has 4 points surrounding with a spline merged at each corner.

07-07-2011, 04:08 PM
Hey thanks people I have made SOME progress with this but stuck again

As you can see from the pictures, the large areas left in the face are those that wont patch and keep coming up with CURVES DO NOT CROSS DIRECTLY

How do I fix this now? Without ruining the model, I havent got a clue what to do to fix this at this stage, because there are that many points and splined I wouldnt know where to start.

Any suggestions?





07-07-2011, 04:18 PM
The easiest thing when you're looking for assistance is to post your model so that others can take a look at it directly.

But judging from the pics, the large areas have more then 4 splines that make up the area. Areas to patch have to either 3 or 4 splines joined at the corners, no more and no less. Anything else won't work.

Are you modeling this head from a tutorial? Because while splines are a perfectly acceptable method of modeling, I don't use them too much for organic modeling. But if you want to use that method, you could get away with far fewer splines.

07-07-2011, 04:24 PM
Yeah mate i'm using the Lightwave V9 Essential Training tutorial from the book Chapter 18 on how to model a human head.

Here is the model...


07-07-2011, 04:59 PM
I will take a look at it. By the way, its probably better if you just attach files and pictures directly to your post with the manage attachments button. I hate downloading things like this off those file servers that make you enter in codes and everyting else(not to mention annoying pop ups)

07-07-2011, 05:22 PM
Thanks much appreciated, apologies for uploading it to Fileserve will use the feature in here in future, thanks.

07-07-2011, 05:29 PM
Ok, here is your model back. I made a copy and pasted it to the 3rd layer and did my edits there. You still had some splines that were not connected in the corner and as I said earlier, you had some areas that were made up of 5 splines and that will not patch. So I created some new splines and removed a few and you can compare it to your original one which is still on the first layer. I also pasted your polygons that you had created and moved them to layer 2. You had several flipped polygons so I made them all face the correct way and merged all the points. I didn't spend a lot of time shaping it up so it might be different then what you had shapewise, but they should all be valid patches that you can now spline patch.

Again, I only use spline patching usually for mechanical models that require a certain amount of smooth contours. For organic modeling, I would recommend you look either into box modeling or point by point (which is my preferred method- aside from zbrush anyway).

By the way, the eye I wouldn't even bother patching. You can just extend the polygons at the edges of the eyes into the eye cavity.

07-07-2011, 06:04 PM
Thank you :D

I managed to patch some more areas I couldnt before, but still some not working for me, I think i've ruined the model somehow lol, stuff like this is really disheartening when Lightwave doesnt do what you want it to, the tutorial in the book should have told me to check I could patch areas as I went along maybe its meant to be a beginners book.

Uploaded the new model.

07-08-2011, 07:25 AM
this may help:

07-11-2011, 06:50 PM
Hrgier thank you I was able to patch the model successfully but I think I made some errors somewhere along the line because when I merged all the points there seems to be bits missing like holes in the head and some pinching.

Any ideas?

Uploaded the updated model.


07-11-2011, 07:19 PM
The reason there are holes is because your patches don't line up correctly. When you select your splines and run the patch tool, you have to make sure that you are creating the number of patches you need so they line up to the ones next to them. You can see the pic below where I've drawn red lines where you could add more polygons so that they line up to the ones next to them.

Of course, you can also just cut the polygons with the knife tool and add divisions where you need them, but its best to get it right from the spline patching because the splines should most closely match the contours/shape of your object.

07-11-2011, 08:22 PM
Ahh I get you thanks :D

Pretty much hit and miss towards the last few spline patches id select them to patch, got the curves error, patch some more go back to that one and it would work, it started patching two splines instead of one if you get me, probs where I went wrong, will post an update tomorrow thanks.

07-12-2011, 02:40 PM
Is it normal to feel this dishearetened when working on a model?

Seriously losing my temper with this now.

I've re-patched the head and theres about 4 squares on the neck that just wont patch no matter how I select them or in which order, also near the top of the head I have a random black polygon and I don't know why.

Also the area at the top of the head that needs patching also encloses the square next to it so it patches the new square and the patch runs into the square at the side of it.

I can't see anything wrong with the way im selecting things.

Uploaded the model so you can see what I mean.

07-12-2011, 04:42 PM
Maybe because I don't have a point where the red is circled in this image, but dont know how to fix that.


07-12-2011, 06:26 PM
Yep. You need those curves to be joined with a shared point. They aren't crossing. Spline modeling can be tedious at first but it is very powerful once you get the rules straight in your head. I've uploaded a corrected head. I used the add points tool in multiply tab. Select one of the splines, add a point to it at the junction you want to achieve. Deselect the point and curve. Select the next spline, add the point. Then select the two points and weld them. (ctrl + w)
Now it should patch fine.
As for the black poly. It looks like a three pointer but it isn't. It's a quad but two of the point are sharing the same space. Select the open edge and use the Drag tool (ctrl + t) and drag the point out and you'll see it's a quad and it'll turn gray. As you can see in the pic.

07-12-2011, 06:58 PM
Thank you so much! Saved me hous of stress lol.

Ive managed to drag out the edge too its no longer black. Now when I go to patch the very top of the head it patches but the polygon still crashes into the one at the side of it and when I merge all points and turn on sub patching it doesnt add up the head correctly if you get me.

07-12-2011, 07:03 PM
Philly85, I just recommended to someone else in another thread that they pick up a copy of Inside LightWave 7 by Dan Ablan. You can buy a used copy for a penny + $3.99 shipping on Amazon here: http://www.amazon.com/gp/offer-listing/0735711348/ref=dp_olp_used?ie=UTF8&qid=1310518538&sr=8-1&condition=used It has the best head modeling tutorial in it anywhere that I've seen and it's pretty easy to follow. This spline patching tutorial that you're using does not seem very good. I am sure you will get better results with the book.

07-12-2011, 07:06 PM
Thanks mate just seen that thread lol, will order it right away :D I'm using Lightwave 10 shoulnt be an issue though should it?

07-12-2011, 07:12 PM
No, won't be a problem as far as modeling goes. Modeling in LightWave has not changed much since those books were out. Obviously it won't cover newwer features but there's still a lot of valuable information in there.

07-13-2011, 08:41 AM
Here are the final 2 problems I seem to be having.