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Wikitude 3.3 radar PNGIDAT: incorrect header check

Wikitude 3.3 radar PNGIDAT: incorrect header check


Today I updated the Wikitude SDK to the lastest version. When I was using the 3.2 sdk I was able to show the radar with any problem and now I'm getting the following error:

Wikitude SDK: Format: PNGIDAT: incorrect header check

Wikitude SDK: IDAT: incorrect header check

Wikitude SDK: Image (1): Unable to load.

Wikitude SDK: Failed to load ImageResouce (1): Unable to load.


¿Do you know what's happening? I actually only changed the initialization code as you stated in the docs. Also I found if I change the line to point to a non-existing image I only get the last line (Wikitude SDK: Failed to load ImageResouce (1): Unable to load) so the SDK is finding the image. In the last try I replaced the images for the ones in the example code and I'm still getting the error. Here is the way I create the radar:


                  var arRadar = {


                    hide: function hideFn() { AR.radar.enabled = false;},

                    setMaxDistance: function setMaxDistanceFn(maxDistanceMeters) { AR.radar.maxDistance = maxdistance; },


                    show: function initFn() {


                        AR.radar.container = document.getElementById("radar");

                        AR.radar.background = new AR.ImageResource("radar_bg.png");

                        AR.radar.northIndicator.image = new AR.ImageResource("radar_north.png");


                        AR.radar.centerX = 0.5;

                        AR.radar.centerY = 0.5;

                        AR.radar.radius = 0.3;

                        AR.radar.northIndicator.radius = 0.0;

                        AR.radar.enabled = true;



                    updatePosition: function updatePositionFn() {

                        if (AR.radar.enabled) { AR.radar.notifyUpdateRadarPosition(); }








Please try following things:

- Clean the project including deleting the derived data folder

- Try using a different png file


If the error persists, please attach to this post the offending .png file and we will have a look at it.

Same here. Only I'm getting that error with EVERY local png in the project since 3.3 update. Also, the JS is not working anymore (not selecting pois, calling to native delegate...) although the same JS code works in the Android version using Wikitude 3.3.

Wikitude SDK: Format: PNGIDAT: incorrect header check

Wikitude SDK: IDAT: incorrect header check


I've re-saved my assets using Photoshop's Save to Web feature without success. Is there any "correct" method to save png files in order to work with this version? Is this a bug?

Wolfang, I actually used the radar png that you have included in the wikitude samples and I also cleaned the project a couple of times. Also I'm not sure if this is important, but my project it's multi language.

Do you need the source code?

Are you seeing this with the sample application as well? The sample uses local pngs.

To get to the bottom of this could you provide additional information: XCode version and iOS SDK version, is the project using any other libraries except the wikitude sdk (especially is any of those libraries using libpng?).

The project would be helpful if the error does not show up in the sample application. If that is the case please send it to forum AT wikitude DOT com or attach it to this post.


Actually the sample APP works great but not in my APP after upgrading to the 3.3 SDK. I rolled back again to 3.2 and the radar shows and I didn't modified anything in my HTML file. Here is the requested info:

- XCode version: 5.1
- iOS version: 6.1 (iPad 2)
- Libraries used: ZBarSDK (probably this one uses libpng)

I will send you later the source code. Thanks Wolfang.


Daniel, have you tried removing the ZBarSDK and trying it withtout linking to it. If it is working that way, this would give us valuable input getting to the bottom of this  issue.


We found a setup to reproduce the issue and we will release a SDK update (3.3.1) within the next days which fixes the issue.

Thanks for reporting the issue!

Best regards

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